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Do publish considerably more of this topic ok. It just seems a little pretentious based on your actual level of fitness. It just made sense to me. I wish you the best of luck on your goals and if you go for it stick with it! Strengthening Knowledge and Understanding of Dietary Supplements.

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It was time for radical action. The Day Intermittent Fasting Challenge. From reading through all the literature, it was clear that the more frequent the fasts the better. No excuses, no bullshit. Just a month of willpower, focus, and intent. Why not give it a try?

Just do one day of fasting. Men, go for 16 hours. If it goes well, try doing it once a week for a month. Find what feels right for you. I wrote this entire article in a fasted state. Learn the 5S Framework to eliminate procrastination and get an instant boost of discipline and productivity even if you're feeling drained or distracted.

If you're new here, you may want to subscribe to my RSS feed. Check it out, there's some truly mind-blowing stuff in there that's sure to make you look at optimal nutrition […]. This is the 3rd article I have read about intermittent fasting. I am 47yrs old, in menapause, having trouble sleeping and need to loose more than lbs. I have been told that this way of life will totally take away any metabolism that I may have left.

Somthing inside me says this may be my way. Do you have any info on how this may work for me. I am a year-old woman, also going through menopause. The health benefits of IF are utterly, utterly worth it, so I encourage you to please give it a try.

I am an almost 50 year old woman who has been struggling with weight and the Big M for about 4 years now. Hot flashes, mood swings, could not sleep through the night no matter what and losing weight was next to impossible.

I decided to start the program with a 24 hour fast — from 1 pm til 1 pm. It was surprisingly easy but I did eat a nice hearty lunch before starting. The first couple of days I could not sleep, I had a headache and I was miserable.

I thought this was not going to be for me. But on day 4 something miraculous happened. I slept through the night!! I woke up and was so excited. And I started noticing less and less hunger pangs. And more and more energy. And fewer hot flashes. Was this a miracle? I would say so. I work out in the mornings in a fasted state and I feel great.

Phil, I'm not sure I understand your math. You wake up at 10am, and have nothing to eat until 7pm. To reach the 16 hours would mean that your last meal was 7 hours before wake-up time, hence 3am? I don't get it. I have my last meal of the day at 7pm, and don't eat anything until 11am. I could get in a workout between the time I wake up and the 11am meal time, but it just feels counter intuitive to basically skip breakfast; I'd be willing to try, though!

Yes you're correct, my last meal is at 3am, right before I go to bed, then next time I eat is 7pm. I edited the post to make it clearer. Yeah the way you proposed would totally work.

The benefits are seen within 2 weeks… could be your secret weapon for the Half Marathon Challenge!!! Well, I don't have 2 weeks before the race. But I will try this for sure, see what happens. Now I only need to find another challenge to motivate me after the race is done and dusted. It just makes this a lot easier!

Another matter for me. Is it ok to keep the practise while on IF? Is it better to do it fasted or not? I figured I would reply because you seem to have a similar situation as me. As for the type of training you should be just fine. It takes time to regulate that kind of change. If anything I would drop your weight a little bit for the workouts while still challenging yourself. You will still benefit in strength gains if not more with this type of eating schedule.

As for upping your CF sessions to 6 times per week.. Mobility also gives you stellar improvements in Overhead Squats and I say this from my own experience. My first couple days I was way more awake than ever before and had trouble falling asleep because my mental function was up and I noticed some headaches and water craving from kicking food addiction, but I have to say my productivity at work which I work 12 hour shifts , as well as my energy lever at the gym is amped!

Other than that you could safely throw in a BCAA supplement before your workouts if you are concerned with muscle break down. I gained about 20 pounds after starting CF from muscular gain and the fact that intense workouts made me super hungry.

Since starting the fast a week ago I have dropped 5 lbs and my skin has cleared up completely. My stress level is way down and my mood is way more positive. I plan to adopt this way of eating as a permanent lifestyle. I wish you the best of luck on your goals and if you go for it stick with it! Thank you for your reply. I tried my first fast this week, starting monday 9pm until tuesday 1pm, so that was 16 hours.

And it was sooo ok to do it, it suprised me! Regarding the mobility training you mentioned, I had not heard of it. At least not with that name. I checked it out and we have a pretty good session before our classes start, although it does not compare to one day totally dedicated to it.

I've had problems with my weight underweight some time, I rarely ate when I was on College last year, I couldn't eat all day, I just managed to eat when I came home in the evening every day. That didn't do me no good. Towards the end of the year I ate less and less and I lost totally 7 kg 15 pound? So in the end, it didn't look so good. Also it didn't feel good. In the last 3 months over the summer I've been eating allot and working out, and I finally managed to put back what I lost, now I'm eating whenever I can, breakfast is the most important, i make meals for college and eat snacks and dinner.

I finally feel great. So just because of that I'm not really confident with this challenge, it sounds a little risky for me: But I can't say it doesn't sound amazing…when I read the effects… I really love challenges like this, but I am afraid a little that it will get me back to that state.

I think you should check out leangains. I know it's hard to believe but it really does look like this protocol could be beneficial for muscle mass gain as well. This will minimise protein breakdown and effects of the fast on the muscle. And then when you do eat, you get the anabolic effect of the fast with the increase of HGH and other processes.

Honestly I think it's worth a shot, 1 day won't hurt and it'll be an experience: Usually for about 16hrs, sometimes a little more or a little less. I found my body naturally gravitated to it once I switched to Paleo eating in January. I'm just not hungry during those hours! I've found it to be so convenient as well, as it's one less meal to shop for, prepare, or worry about.

And as you mentioned above, when I do eat it always tastes fantastic! I have great energy, my blood sugar and moods are stable, and it definitely helps with fat loss. Have you read "Healthy at " and "Dare to be "? Great books on the topic. And btw I think it's totally within our power to live to and be fully healthy. But these days I'm focusing on learning how to most enjoy the present: I haven't heard of those books but will check them out.

I also think it's completely possible to live beyond in a good state of health; body and mind both. Enjoying the present is definitely important, too!

By acknowledging each day I think we learn to enjoy the journey rather than just training our sights on the end-goal. Definitely a more fulfilling and fun way to live IMO: I was just thinking about doing a cleanse. Never tried one before so I thought it might be a good idea to clean out the old system. I was actually worried about the not eating part though because like you I have always been a believer of the six meals per day. I am going to take a look at some options for cleansing and also take your research into consideration to try to combine the forces and get some great results.

I will let you know how it goes. My main goal is to get rid of excess foods that have not digested in my body and sort of hit a reset button.

Any cleanse that you have done or heard about that you can recommend? Also I have been thinking about digestion lately because of the Gracie diet. As you probably know the Gracie family developed a diet that basically gives food combinations that allow for easy digestion. Although I eat a fairly healthy and balanced diet I find at times that my combinations or timing of meals causes poor digestion high energy consumption and even a heavy feeling in the stomach at times.

I think that fasting may help me listen to my digestive system by making it silent for a few hours so that it is easier to pay attention when it does speak up again… if you know what I mean. Anyway I will re share this for sure man.. Yeah I didn't find any specific evidence of the cleansing effect, but I personally believe it. When the body has no food to digest, the liver and other organs can focus on cleansing processes instead.

As far as specific cleanses, I tried my own last week, made like 3L of fresh lemon juice and drank a big glass every morning..

It worked well but it was rather, extreme. I know about the Gracie Diet, I love listening to Rener's philosophy on food. I've definitely integrated some of their principles in my own diet. That way you're guarantee to have some live enzymes to help the digestive processes.

I do the Warrior Diet and fast every day about 14 hours before my workout and recovery meal, then fast the rest of the day most days till 6! I turn 41 this Saturday…. I've gotten guesses on my age as being early 30s… it's great! Did you find that it got a lot easier as you went on? Do you still get hungry in the middle of the fast?

I'm a little hesitant on this one as well, as I also eat about 6 meals a day, but I'm on day 10 of the cold shower challenge and I absolutely love it, so I might as well trust you on this too! Nice congrats on making it through the first 10 days of the Cold Shower Challenge! The hardest part is definitely behind you. Give it a try for 1 day.. Honestly if it works, you'll be so happy you don't have to worry about eating all the time.

I'm definitely keen to give it a go. I was wondering though and this may sound stupid … is it still fasting if you're asleep? I've heard perhaps incorrectly that the digestive system slows right down when you're asleep so technically if you eat before going to bed isn't the food just sitting in your gut waiting?

So yeah in practicality, if you sleep for 8 hours you only really consciously fast for 8 hours, it's not that bad at all. And could it really make that much of a difference?

Everythign is backed by science the links are in the article below the health benefits facts. Have you thought about doing your workout fasted having your first meal post-workout? Today Grokker phildrolet posted a blog on IF. Amazing how religous ceremonies of ancient times have impact on our body machines. If they knew it all allong without the state of the art science of today. I will start tomorrow with the fasten challenge for a month and will do it 1 day on, 1 day of.

I'l wait till the sunset before I enhance eating. Yeah it's interesting how fasting actually is instrumental in certain cultures yet for reasons totally different than those outlined in this article. Good job for stepping up to the challenge! I reckon 1 day off 1 day on is perfect, I'm thinking it's what I'll settle down for when I'm down with the 28 days..

Fasting everyday is not easy ahha. I've been wanting to do IF since reading about it in the 4HB. Tim does it once a week and it coincides with cheat day on the slow-carb diet, so once you're done you have free reign on whatever you want to eat. I started doing Occam's Protocol again yesterday and am committed to doing 2 more weeks of it, but I'm gonna add a secret weapon to it: IF once a week. If the HGH spikes it should allow for even more massive growth.

Plus I started eating white meat again, aiming for 5kg of muscle gain in 2 weeks. If our little Perth experiment proved anything, this is more than possible. Do you think IF on workout days would be the best way to do it?

I'm just worried if it's done on a workout day, my body's not going to have any fuel for the workout. I'd recommend you look at http: I'm definitely interested to hear how it goes.. I can't get over the 20x HGH levels.. Took a long look at leangains. Looks like working out in a fasted state is actually recommended, with a massive meal right afterwards.

I did that today, big time! Dude I was bottomless it was awesome haha. But for most of us that are not, would results be similar if we went to bed at midnight 12am, do a 16 hour fast, huge meal at 4pm, then small meals at 7pm, 10pm and then midnight right before sleeping?

Yes I do polyphasic sleeping- I generally sleep from 3am to 9am then take a 1 hour "napatation" 30 minutes meditation, 30 minutes nap later on, either around 5pm or 9pm depending on my workout schedule.

Anyways, yes the protocol would absolutely work on a more "regular" sleep schedule like the one you wrote. I'm into paleo nutrition, crossfit, and ocassion intermittent fasts whenever it feels natural. I want to know if you have any scientific qualifications for advocating women try a 14 hour fast compared to the 16 hour male fast.

If you don't, I want to ask you sup with that? Because in my research forays into IF I've never seen any mention that women shouldn't fast as long because of physiological reasons. Thanks for your question. I've based my recommendation on the Leangains program which has been having tremendously successful results for many years.

You can find out more here http: Also, check out this interview with Martin Berhkhan http: It appears that women will have lower blood glucose level after fasting, which makes the fast more challenging. But as with anything, I recommend self-experimentation. Find what works for you.

But generally speaking, it appears that 14 hours is a good guideline for most women. If you can do more without negative effects though, I'd imagine there would be benefits to doing so. This style of eating totally appeals to me right now since I find I'm only really hungry within certain hours of the day, and I'm eating at others because I'm supposed to i. Would love to hear your thoughts or maybe you can point me to resources on results of IF in endurance athletes.

These days running is my primary fitness focus, with a little yoga and strength training thrown in for fun and balance. All in all I believe IF for endurance athletes is great, but it's a fairly novel concept, hence why I'm running this little experiment on myself: I have to fast now….

Hahah dude you know you love it: P Stepping out of our comfort zone, a little bit more each day.. The Warrior Diet is very easy to do. Then I fast the rest of the day on tea, Master Cleanse lemon drink, etc. I'm rarely hungry and if I do feel hungry most days I tough it out. I'm a little plateaued at the moment but am going to increase my weights and lower my carbs several days a week over the fall and winter to prevent regain. Actually I'm starting to think this way of eating may have stabilized my weight indefinitely.

I am underweight somewhat but at least I'm not losing more muscle and gaining body fat like I was before. IF is good for that. I'm at Day 20 of the Challenge and it's going well but definitely will be looking to try something a bit different once this is done. Maybe do IF 3 days a week and something else a bit less extreme on the other 4 days? It's going to be hectic!

I gotta get in touch with the researchers actually to get a second sample in a couple weeks. Not fasted for ages, first one of a new weekly regime starts today 4pm — 7am. Going for 15 hours because it fits..! Yo chienne, j'ai pas tout lu, mais que est-ce que tu crois que l'efficacité de cette méthode a un lien avec avec le fait que le corps fait le bilan des liquides quotidiennement et le bilan des solides à tous les jours.

Je sais pas trop honnêtement! Je connais pas encore ce principe la, on en jasera dans le temps des fetes! My motivation to train hard, develop my Jedi Mind Tricks, try crazy experiments, and work hard on becoming the best Phil Drolet reached unprecedented heights.

I really started […]. Not only does it allow you to experience and feel what other unfortunate people around the world are feeling BUT it also has a lot of health benefits like you stated in the article!

Also, there is a lot of other tips about diet in our book that I believe have been backed up by studies to show their benefit for as far as I know, if you are interested I will put in the time to translate and put it up here: I read up on your cold shower challenge a few months back and I had to do it! Now that the cold showers are a routine, I would love another challenge and it looks like that I found it. Btw, i personally found fasting to be easier than the cold showers.. But, I want to say this, My finace and I went on a 21 day water fast nothing but water for 21 days though harsh but I do understand what you are saying about the benefits.

Within 3 days on the water fast, my breathing was tremendously improved,my old sports injury of 5 years was healed, greater mental clarity, and greater ease of movement. Damnnn 21 day water fast??? Must have been pretty wild by the end.. Did you feel really weak? My nose was always sorta half blocked which totally annoyed me, and within 3 days, boom, perfect breathing. I personally found fasting to be easier than the cold showers..

But, my fiance someone who has competed in ironman competitions and very health conscious he at the end felt very weak. He went from to in the 22 day water fast. We only consumed distilled water for they say it was the best water for fasting. With the information that energy not being used for digesting goes into healing the body and renewing body parts and a higher sense of mental clarity.

We had to do it! But, we did this for spiritual reasons and health reasons. So, thank you Phil for helping me change my life. For I believe in you and the feel good lifestyle. Uhuu, another great article! And this one comes just in time yeah, a sign from the Universe! My way — twice a week for 24 hours. And about the training while fasting — last time I decided to have my Karate class on a fasting day — was great! Absolutely no lack of energy, would say even the opposite.

Made from high-quality Gyokuro green tea leaves that are crushed and pulverized, Matcha Green […]. Hey good article, and very informative. Did you mean increased insulin sensitivity in the benefits column? Insulin resistance is associated with diabetes, weight gain as well as Polycystic Ovarian syndrome. Hey Callie, thanks for your kind words and for the heads-up. It just seems a little pretentious based on your actual level of fitness.

You should be eating about 3 12oz steaks a day, before the next girl you shake hands with breaks your arm off. Do you think that the 4 hour body testosterone boost of 3 brazil nuts, vit d and fermented cod liver oil before bed and upon waking would effect the fast? I eat between 11am-7pm and take these at 8am and 11pm. I wanted to know what your macros and calorie breakdown was for it on training day and rest days or what you think worked best.

I am a bit late to this article but just read it after checking out other info on the web about intermittent fasting. Anyway, I wanted to say thanks for the article it was one of the best and most honest ones I found. I started intermittent fasting today and so far have fasted for 15 hours.

I plan to break the fast with a salad in the next hour or so which I am looking forward to immensely! I will then eat another healthy but substantial meal to then fast again until tomorow. I have to say it was actually much easier than I ever imagined with the odd grumble which actually was vaguely pleasant!

I realise that I do not normally allow myself to get to the point of being hungry like there is something wrong with that normal feeling!? The danger I guess there is that when you feel the hunger pangs you then reach for the biscuit barrel or some other non-ideal food for a quick fix.

Since those foods are not a big issue for me I am hoping this way of eating can work for me long term for optimum health. Love this whole site btw. So much great material. Keep up the excellent work and thank you for helping me improve my life. OUr body is incredibly adaptable. So…you walked to the grocery store but drove home? Not a big deal but these are the sort of little inconsistencies that make me question your credibility. Come on dude — proof read or something!

I just find out your blog today and reading it for 6 hours now. Just wanted to let you know your blog rocks and keep up the good work. I am from Turkey and I am a muslim. We have a fasting month which is coming up nearly in next month. According to our religion, in fasting month Ramazan we are not allowed to eat or drink between the sun rise and sun set.

But after reading this article I think I will starting fasting a little bit earlier this year: Yesterday I have read your article http: I started lumosity, doing more exercise, and I want to get started with intermittent fasting too.

As far as I know your body needs a certain amount of vitamines and stuff like protein, carbohydrates, etc, each day. So does that mean that you basically have to eat all of it in one meal? Diets that tell me to eat less always scare the hell out of me, because I am a big believer of eating a lot but not too much. So I hope IF is about eating less frequently, but not less? If it really is about eating less, then please tell me how it fills in for the daily amount of vitamines, proteins, carbohydrates and stuff you need.

In Intermittent Fasting, you still want to consume roughly the same amount of food as you would usually, except you compress it into a smaller period of the day.

Will be a good challenge though! Thanks for a great article on intermittent fasting that is not overly technical, but still speaks to the science behind it. I have a few questions and wonder if you would be so kind as to answer them. You mentioned somewhere — maybe in a comment to a post? Did you do that? How is it working for you? This from someone who always had to eat immediately upon waking and then every several hours. That brings me to my next question.

Mostly I run and bike, which was why I was especially happy to see someone like you trying out the intermittent fasting. What do you eat for your first meal post-fast? I think different athletes have different nutritional needs, according to their sports and goals. Ah, is there a follow-up to this article? Did you create this website yourself or did you hire someone to do it for you? I also have a virtual assistant from India who helps me with some of the technical tasks regarding optimizing the layout and such.

I fast from 3 or 4 until7 or 8am which suits me fine! I used to be very light and am looking forward to returning to that weight! I took a little break myself and decided to get back to it tomorrow. Not long ago i stumbled on your document and still have already been looking at coupled.

I would like to study modern content and also to reveal my personal feelings along with you. Thanks for the motivating article!

I just stumbled across IF haphazardly last week. I went Paleo a year ago and it has done wonders for me physically, mentally and emotionally. That being said, I had hit a plateau and wondered if I would be able to lose literally the last 10 lbs? On Saturday I did the 24 hr 8pm-8pm fast.

Yeah I think IF is the best way to lose that pesky last 10lbs it was for me anyways. I switched from the Leangains method to two 24hr hour fasts during the week. I find this method to fit in better with my lifestyle…. So far I lost 2 lbs, not a huge difference, but finally the scale is moving…and in the right direction!

Oh by the way, there was a fasting documentary on the BBC. You can catch it on YouTube http: Thanks a lot for sharing the link to the documentary, I look forward to watching it. Will it still be as beneficial in these hours. I suffer from chrohns disease and looking at new ways to combat it.

Also, if the first meal after training is the biggest does that mean the following two meals are smaller? Today I had 2 meals with meat and veg and subway. Any help for a newbie would be sensational. Yeah like you said, the first meal after the workout is the biggest one and the 2 other ones are smaller not small, just smaller. Really easier than I thought. Keep it up Chuck! I really like IF. Even after 16 hrs of zero calories my mind is clear and focused and my weight training is better than ever.

I also started cold showers and quit coffee about a week ago. I usually run, not jog, in the morning and have a cayenne pepper and v8 cocktail at the end of my 8 hr eating period. I think the cold showers and high intensity cardio is is important to keep my metabolism from slowing. Keep the strategies coming. Your reference articles are for intermittent whole day fasts an dthis is the only material I can find too.

Hey guys i am doing tapout xt, this will be my 3rd week of doing it, and today i am doing the 24hr. So far it is going pretty well, but i did cheat and got up at around 8 a. I will also include some kettlebell workouts during the week!

Thanks for taking the time to read my comment! My best advice to you honestly is to experiment with it! What do you eat after your fasts as it seems counter intuitive to all the things that I know about health and nutrition to slow down the metabolism through starvation all day and then eat one big meal before bed so that it sits in your inactive body all night.

What foods do you eat that late at night as I was always taught no carbs after 6pm and how do you feel about what I was saying?

What foods do you eat that late at night as I was always taught no carbs after 6pm and how do you feel about what I was saying. I just found out about IF a few days ago.

I wake up, go to school and eat at about 8 in the morning and again around I been wanting to lose weight for basketball and this girl I like. Today, I found myself after a 2-hour workout having enough energy and the mood to walk 4 miles back to my home.

No Bullshit, No Excuses. Thanks for the great article. First, I got myself down to a lower eating window 2: But I am unable to workout until around 7p. Also, to give myself energy in the morning I have been drinking an energy drink called Rockstar Xdurance, It has 20 calories and 2 grams of sugar. Will drinking this during my fasting time break my fast? Calories in these shakes are variable, but tend to be lower than your average meal replacement shake.

Carbohydrate content in these low-carb meal replacement shakes starts from 0 grams. Strawberry Smoothie Recipe with Goji Berries. Protein Coffee Smoothie Recipe.

Total Body Dumbbell Workout Plan. How to get through a tough workout. Tone every inch — total body workout. Most research on capsaicin and other capsaicinoids focuses on their effects on energy intake and appetite, rather than body weight.

A meta-analysis of eight randomized, placebo-controlled clinical trials evaluated the effects of capsaicinoids on ad libitum energy intake in a total of participants who had a normal body weight or were moderately overweight [ 78 ].

Doses of capsaicinoids ranged from 0. Overall, consuming capsaicinoids significantly reduced energy intake by a mean of 74 kcal per meal; body weight was not assessed, so the impact of this calorie reduction on weight loss cannot be quantified. The authors noted that the results suggest that at least 2 mg capsaicinoids are needed to reduce calorie intake but that the studies were very heterogeneous. However, the calorie reductions did not significantly affect body weight at either 6 weeks or 12 weeks.

It might also increase serum insulin and reduce high-density lipoprotein HDL cholesterol levels. Otherwise, capsaicin and other capsaicinoids appear to be safe.

Research is underway to reduce the pungency and "chili taste" associated with capsaicin while retaining its potential biological effects [ 81 ]. Carnitine is the generic term for several compounds, including L-carnitine itself, several acylcarnitines e. It is composed of the amino acids lysine and methionine [ 84 ].

Carnitine is naturally present in animal products such as meat, fish, poultry, and milk and dairy products; small amounts are present in some plant foods. Humans synthesize carnitine from its constituent amino acids, so dietary carnitine intake is not necessary. Almost all cells of the body contain carnitine, which transports fatty acids into the mitochondria and acts as a cofactor for fatty acid beta-oxidation [ 85 ]. Because of these effects, carnitine has been proposed as a weight-loss agent.

A systematic review and meta-analysis combined the results from nine carnitine supplementation clinical trials in adults including the two described above that assessed weight loss [ 85 ]. The trials included a total of participants. In eight trials, the daily carnitine doses ranged from 1. Overall, study participants who received carnitine supplements lost an average of 1. Additional research on carnitine for weight loss is warranted.

Rarer side effects include muscle weakness in patients with uremia and seizures in those with seizure disorders. Some research indicates that intestinal bacteria metabolize carnitine to form trimethylamine N-oxide TMAO , a substance that might increase the risk of cardiovascular disease [ 91 ].

This effect appears to be more pronounced in people who consume meat than in vegans or vegetarians. The implications of this effect are not well understood and require more research.

Chitosan is a manufactured polysaccharide that is commercially prepared from the exoskeletons of crustaceans. It is purported to promote weight loss by binding to some dietary fat in the digestive tract, preventing its absorption [ 16 , 41 ]. Chitosan might also decrease cholesterol absorption [ 16 ]. Chitosan capsules taken before meals total of 2. However, the amount of fat that the chitosan trapped would result in a loss of only 1 lb body fat over about 7 months.

Chitosan had no significant effect on fecal fat excretion in the women compared to the control group. At the end of the study, those in the treatment group lost a mean of 1 kg body weight compared to a mean weight gain of 1. In this study, chitosan treatment reduced body weight mean weight loss about 2.

The authors of a Cochrane review that included 13 trials examining the effect of chitosan on body weight found that chitosan, when taken for 4 weeks to 6 months, reduced body weight by a mean of 1. They concluded that chitosan appears to be more effective than placebo for short-term weight loss, but most studies have been of poor quality. The authors also noted that results from high-quality trials indicate that chitosan has minimal effects on body weight, and these effects are probably clinically insignificant.

The adverse effects of chitosan are minor and primarily involve the gastrointestinal tract. They include flatulence, bloating, mild nausea, constipation, indigestion, and heartburn [ 93 , 95 , 96 ]. Because chitosan is derived from shellfish, people who are allergic to shellfish could theoretically be allergic to chitosan [ 97 ].

The trivalent form of chromium chromium III is an essential trace mineral that potentiates the action of insulin. Dietary supplements commonly contain chromium in the form of chromium picolinate, which consists of chromium and picolinic acid, although they might also contain other forms, including chromium nicotinate and chromium yeast [ 99 ].

Poor chromium status might contribute to impaired glucose tolerance and type 2 diabetes [ 98 ]. Researchers have hypothesized that chromium supplements increase lean muscle mass and promote fat loss, but study results have been equivocal [ 41 , ]. Some research indicates that these supplements might also reduce food intake, hunger levels, and fat cravings [ ], although data on these effects are sparse.

Several studies have evaluated the effects of chromium supplements, usually in the form of chromium picolinate, on weight loss. Six of the trials included resistance or weight training, and three did not.

Chromium picolinate supplementation reduced body weight by 1. Also in , a systematic review and meta-analysis of 11 randomized controlled trials including most of the trials evaluated in the Cochrane review examined the effects of chromium supplementation in a total of overweight or obese individuals [ 99 ].

The authors concluded that daily doses of to 1, mcg chromium for 8 to 26 weeks reduce body weight by 0. Like the authors of the Cochrane review, these authors noted that the effect is small and of "uncertain" clinical relevance. Similar findings were reported from an earlier meta-analysis of 12 trials [ ].

Trivalent chromium appears to be well tolerated. Adverse effects from clinical trials include watery stools, headache, weakness, nausea, vomiting, constipation, vertigo, and urticaria hives [ 99 , ]. Chromium does not have an established UL because few serious adverse effects have been linked to high intakes [ 98 ]. Hexavalent chromium chromium IV is toxic and not found in food or dietary supplements. Cola or kola nut see section on caffeine above. Forskolin is a compound isolated from the roots of Coleus forskohlii , a plant that grows in subtropical areas, such as India and Thailand.

Forskolin is purported to promote weight loss by enhancing lipolysis and reducing appetite [ , ], possibly by stimulating cyclic adenosine monophosphate cAMP production. This increased cAMP production, in turn, is thought to activate lipase and promote the release of fatty acids from adipose tissue [ 16 ].

Although animal studies indicate that forskolin reduces food intake [ , ], research in humans is very limited and inconclusive. Compared to placebo, Coleus forskohlii extract had no effect on body weight, appetite, caloric intake, or macronutrient intake. In a study in mice, Coleus forskohlii extract caused dose-dependent hepatotoxicity, but pure forskolin did not have this effect, suggesting that other component s of Coleus forskohlii extract might be responsible for the hepatotoxicity [ ].

Forskolin has not been evaluated in longer-term trials. Additional research is needed to better understand the safety and side effects of both short- and long-term use. Conjugated linoleic acid CLA is a mixture of linoleic acid isomers containing conjugated double bonds that is present mainly in dairy products and beef. Researchers have suggested that CLA enhances weight loss by increasing lipolysis and fatty acid oxidation in skeletal muscle, reducing lipogenesis, and promoting apoptosis in adipose tissue [ 17 , ].

Although CLA appears to reduce body fat mass in animals [ 17 ], results from human studies suggest that its effects are small and of questionable clinical relevance [ ].

One double-blind, placebo-controlled trial evaluated the effects of CLA supplementation as a Participants received CLA as a free fatty acid 3. At the end of the study, body fat mass dropped by significant amounts with both forms of CLA compared with placebo; reductions, on average, were 6. Supplementation with CLA as a free fatty acid but not as a triacylglycerol also increased lean body mass compared with placebo.

In another double-blind crossover trial, daily supplementation with CLA oil 6. These findings are similar to those from a randomized, double-blind, placebo- controlled trial in 63 overweight or obese adults BMI 24—35 that found statistically significant, but small, reductions in mean weight 0. In contrast, those in the placebo group did not lose a significant amount of body weight 0. The authors of a systematic review and meta-analysis of seven randomized controlled trials concluded that taking 2.

However, the authors noted that the "magnitude of these effects is small, and the clinical relevance is uncertain. CLA appears to be well tolerated. Most reported adverse effects are minor, consisting mainly of gastrointestinal disturbances, such as abdominal discomfort and pain, constipation, diarrhea, loose stools, nausea, vomiting, and dyspepsia [ 3 , , , , , ].

CLA might also increase some markers of oxidative stress and decrease breastmilk fat levels, but additional research is needed to confirm these effects [ ].

CLA has been linked to hepatitis in three case reports [ ]. However, whether CLA caused this toxicity cannot be definitively established because the products were not analyzed to rule out the presence of a contaminant. CLA might adversely affect lipid profiles, although results from studies are inconsistent.

Some research indicates that CLA has no major effect on lipid profiles, but other research shows that certain CLA isomers might decrease HDL cholesterol and increase lipoprotein a levels [ , , , ]. The CLA isomer t10cCLA has also been reported to increase insulin resistance and glycemia in obese men with metabolic syndrome [ , ]. Fucoxanthin is a carotenoid in brown seaweed and other algae. Results from laboratory and animal studies suggest that fucoxanthin might promote weight loss by increasing resting energy expenditure and fatty acid oxidation as well as by suppressing adipocyte differentiation and lipid accumulation [ , ].

Only one clinical trial has been conducted on the possible weight-loss effects of fucoxanthin. The safety of fucoxanthin has not been thoroughly evaluated in humans. Garcinia cambogia is a fruit-bearing tree that grows throughout Asia, Africa, and the Polynesian islands [ ]. The pulp and rind of its fruit contain high amounts of hydroxycitric acid HCA , a compound that has been proposed to inhibit lipogenesis, increase hepatic glycogen synthesis, suppress food intake, and reduce weight gain [ 6 , 15 , , , ].

Studies in rats have found that Garcinia cambogia suppresses food intake and inhibits weight gain [ 3 ]. In humans, however, the evidence on whether Garcinia cambogia or HCA is effective for weight loss is conflicting, and any effects it has appear to be small [ 6 , 17 , ]. In one randomized, placebo-controlled trial, 89 mildly overweight women mean BMI Women receiving Garcinia cambogia lost significantly more weight 3.

However, Garcinia cambogia did not alter appetite, and the study produced no evidence that the supplement affected feelings of satiety. Participants in both groups lost weight, but the between-group weight-loss differences were not statistically significant.

HCA also had no effect on body fat loss. A review and meta-analysis of 12 randomized controlled trials with a total of participants examined the effects of Garcinia cambogia on weight loss [ ]. Therefore, the effect of Garcinia cambogia on body weight remains uncertain. The reported adverse effects of Garcinia cambogia and HCA are generally mild and include headache, nausea, upper respiratory tract symptoms, and gastrointestinal symptoms [ , , ].

However, dietary supplements containing Garcinia cambogia have been implicated in three cases of mania, which might have been caused by the serotonergic activity of HCA [ ].

Symptoms included grandiosity an unrealistic sense of superiority , irritability, pressured speech, and decreased need for sleep. Reports have also described 10 cases of liver toxicity, resulting in one death and two liver transplants, in people taking products containing Garcinia cambogia [ 43 , ]. In most of these cases, the products contained other botanical ingredients and minerals as well, so the toxicity cannot be definitively attributed to Garcinia cambogia.

Because all clinical trials of Garcinia cambogia and HCA have been short, its long-term safety is unknown. Glucomannan is a soluble dietary fiber derived from konjac root Amorphophallus konjac that can absorb up to 50 times its weight in water [ 16 ].

Like guar gum, glucomannan has been proposed to increase feelings of satiety and fullness and prolong gastric emptying by absorbing water in the gastrointestinal tract [ 16 , , ].

It might also reduce fat and protein absorption in the gut [ 16 ]. Glucomannan appears to have beneficial effects on blood lipids and glucose levels [ ], but its effects on weight loss are inconsistent. At the end of the study, glucomannan produced significantly greater weight loss mean loss of 2. In another study conducted in the United States, supplementation with glucomannan 3. Eight weeks of glucomannan supplementation 1. The authors of a systematic review of six randomized controlled trials with a total of participants concluded that 1.

Similarly, a meta-analysis of eight trials that included participants found that glucomannan did not significantly affect weight loss compared to placebo [ ]. The authors of an older meta-analysis of 14 studies designed primarily to investigate glucomannan's effect on lipid and blood glucose levels concluded that 1.

Little is known about the long-term safety of glucomannan. Glucomannan appears to be well tolerated for short-term use, with minor adverse effects, including belching, bloating, loose stools, flatulence, diarrhea, constipation, and abdominal discomfort [ , , , ]. The use of tablet forms of glucomannan was reported to be associated with seven cases of esophageal obstruction in — in Australia [ 99 ]. Users should therefore be cautious when taking glucomannan tablets. Powdered and capsule forms have not been associated with this effect [ ].

The seeds or beans of the coffee plant Coffea arabica, Coffea canephora, Coffea robusta are green until they are roasted. Compared to roasted beans, green coffee beans have higher levels of chlorogenic acid.

Green coffee extract, probably because of its chlorogenic acid content, inhibits fat accumulation in mice and humans by regulating adipogenesis. Green coffee extract also modulates glucose metabolism [ ], perhaps by reducing glucose absorption in the gut [ ].

Green coffee beans contain caffeine see section on caffeine above [ ], although decaffeinated forms are available [ 16 ]. In mice, green coffee bean extract in combination with a high-fat diet significantly reduced body weight gain and fat mass [ , ]. Only a few clinical trials have examined the effects of green coffee bean on weight loss in humans, and all were of poor methodological quality. The researchers concluded that green coffee extract has a moderate but significant effect on body weight mean weight loss of 2.

The authors of another small clinical trial claimed to show a benefit of green coffee extract for weight loss [ ], but the study was strongly criticized by the Federal Trade Commission for having several critical flaws in its design [ , ]. Two of the three study authors subsequently retracted the journal publication. Green coffee extract appears to be well tolerated, but its safety has not been rigorously studied.

Reported adverse effects include headaches and urinary tract infections [ ]. The caffeine naturally present in green coffee beans acts as a stimulant and can cause adverse effects, depending on the dose and whether it is combined with other stimulants see section on caffeine above.

Green tea Camellia sinensis is a popular beverage consumed worldwide that has several purported health benefits [ ]. Green tea is present in some dietary supplements, frequently in the form of green tea extract. The active components of green tea that are associated with weight loss are caffeine see section on caffeine above and catechins, primarily epigallocatechin gallate EGCG , which is a flavonoid [ 41 , ].

A typical brewed cup of green tea has about — mg catechins [ ] and 45 mg caffeine. It has been suggested that green tea and its components might reduce body weight by increasing energy expenditure and fat oxidation, reducing lipogenesis, and decreasing fat absorption [ 41 , ]. Green tea might also decrease carbohydrate digestion and absorption [ ].

Available green tea extracts cover the range from minimally processed tea leaves to highly processed, manufactured concentrates of single constituents, such as EGCG. The authors of a meta-analysis of six randomized controlled trials with a total of 98 participants found that caffeine alone or in combination with catechins significantly increases energy expenditure in a dose-dependent fashion compared with placebo [ ].

This effect might be important for maintaining weight loss by helping counteract the decrease in metabolic rate that can occur during weight loss. Catechins combined with caffeine also significantly increase fat oxidation, but caffeine alone does not. Other human research indicates that EGCG alone does not increase resting metabolic rate, fat oxidation, or the thermic effect of feeding the increase in metabolic rate associated with the digestion and absorption of food [ , ].

Taken together, these findings suggest that green tea catechins and caffeine might act synergistically [ 41 , , ]. Several human studies have examined the effects of green tea catechins on weight loss and weight maintenance. A Cochrane review analyzed the results from 14 randomized controlled trials of green tea preparations in a total of 1, overweight or obese participants [ ]. The trials lasted from 12 to 13 weeks, and doses of green tea catechins ranged from to 1, mg; in 10 of the 14 trials, the green tea preparations contained caffeine.

Green tea supplementation reduced body weight by a mean of 0. However, when the authors analyzed the six studies that were conducted outside of Japan where study methodologies were less heterogeneous than in the Japanese studies , they found no statistically significant difference in weight loss for green tea compared to placebo. The authors reported that green tea catechins combined with caffeine over a median of 12 weeks modestly yet significantly reduced body weight by a mean of 1.

Only two studies in this meta-analysis examined the effects of green tea catechins alone. Their results suggest that green tea catechins alone do not affect body weight or other anthropometric measurements. A meta-analysis of 11 randomized controlled trials found that people who took EGCG combined with caffeine for 12—13 weeks lost a mean of 1. In , EFSA examined health claims related to green tea and concluded that "a cause and effect relationship has not been established between the consumption of catechins including EGCG from green tea…and contribution to the maintenance or achievement of a normal body weight" [ ].

Taken together, the findings of these studies suggest that if green tea is an effective weight-loss aid, any effect it has is small and not likely to be clinically relevant [ , ]. No adverse effects have been reported from the consumption of green tea as a beverage [ ].

For green tea extract, most reported adverse effects are mild to moderate, and they include nausea, constipation, abdominal discomfort, and increased blood pressure [ ]. Toxicology studies in rats and mice show that green tea extract does not cause cancer but does cause nonneoplastic lesions in many areas of the body, including the nose, liver, and bone marrow [ ].

Other evidence in mice shows that high doses of catechins cause liver toxicity. There is also increasing evidence in humans that green tea extract might cause liver damage, though the underlying mechanism is not well understood [ ]. An analysis of 1, postmenopausal women participating in the Minnesota Green Tea Trial found that women who consumed green tea extract containing 1, mg total catechins including mg EGCG and Consumption of some green tea extracts—primarily ethanolic extracts of green tea—has also been linked to liver damage in at least 50 case reports since [ 43 , ].

In , the U. Pharmacopeia USP systematically reviewed the safety of green tea products [ ]. The USP noted that problems are more likely when green tea extract is taken on an empty stomach and, therefore, advises taking green tea extracts with food to minimize the possible risk of liver damage.

Other researchers and medical experts advise using dietary supplements containing green tea extract only with caution [ ]. Guarana see section on caffeine above. Guar gum is a soluble dietary fiber derived from seeds of the Indian cluster bean Cyamopsis tetragonolobus [ 16 , ].

Guar gum is present in certain dietary supplements and is an ingredient in some food products, especially gluten-free baked goods, because it helps bind and thicken these products. Like glucomannan, guar gum is purported to promote weight loss by acting as a bulking agent in the gut, delaying gastric emptying, increasing feelings of satiety, and, theoretically, decreasing appetite and food intake [ 16 , ].

However, guar gum does not appear to enhance weight loss. In a meta-analysis of 20 randomized, double-blind, placebo-controlled trials that statistically pooled data from 11 trials, Pittler and colleagues evaluated the effects of guar gum for body weight reduction in a total of adults [ ].

Trial participants included people with hypercholesterolemia, hyperlipidemia, or type 1 or type 2 diabetes; menopausal women; and healthy volunteers. Compared with placebo, guar gum had no significant effect on weight loss. The authors concluded that guar gum is not effective for body weight reduction.

Reported adverse effects for guar gum are primarily gastrointestinal and include abdominal pain, flatulence, diarrhea, increased number of bowel movements, nausea, and cramps [ , , ]. Case reports indicate that guar gum can cause severe esophageal and small-bowel obstruction if taken without sufficient fluid [ , ]. However, these reports were about a guar gum product that is no longer available [ ]. In their meta-analysis, Pittler and colleagues concluded that given the adverse effects associated with the use of guar gum, the risks of taking it outweigh its benefits [ ].

Hoodia gordonii is a succulent plant that grows in the Kalahari Desert of southern Africa. The San people have traditionally used hoodia as an appetite suppressant during long hunts. This anecdotal evidence, combined with results of a few animal studies indicating that hoodia reduces food intake [ ], led to the widespread marketing of hoodia as a weight-loss supplement in the United States in the early s.

Scientists have not determined the exact mechanism whereby hoodia might suppress appetite. A glycoside commonly called P57, which may have central nervous system activity [ ], is widely believed to be the main active ingredient, although not all researchers agree [ 16 , ]. Despite its popularity as a weight-loss supplement, very little scientific research on hoodia has been conducted in humans [ ].

Compared to placebo, hoodia extract had no significant effect on energy intake or body weight. Hoodia has been reported to cause significant increases in heart rate and blood pressure [ ]. It also raises bilirubin and alkaline phosphatase levels which may indicate impaired liver function , although the clinical significance of these findings is unclear because hoodia has not been reported to affect levels of other liver enzymes.

Other side effects include headache, dizziness, nausea, and vomiting. In the past, some hoodia products were found to contain little or no hoodia [ ]. Maté see section on caffeine above. The human microbiota, which outnumber human cells by up to fold, have myriad roles in human health [ , ].

Although microbes are found throughout the human body, the vast majority inhabit the colon. The gut microbiota play an important role in nutrient and energy extraction from food. Research in mice suggests that the gut microbiota affect not only energy utilization from the diet, but also energy expenditure and storage within the host [ ].

Whether these effects translate to humans is not yet clear. However, manipulating the gut microbiota has been proposed as a method to prevent or treat obesity in humans, and probiotics might provide a way to accomplish this.

Probiotics are in foods such as yogurt as well as dietary supplements. The many different strains of probiotics include lactobacilli, streptococci, and bifidobacteria, which all have widely varying effects in the body [ , ].

Most of the research on probiotics and its influence on the gut microbiota and obesity has been in mice, and the results have been promising. For example, probiotic supplementation reduced body weight gain and fat accumulation in obese mice fed a high-fat diet [ ]. A limited number of human clinical trials have been conducted and have had inconsistent results.

However, a systematic review and meta-analysis of four randomized controlled trials including the one described above found no significant effect of probiotics on body weight or BMI [ ]. The researchers noted that the limited number of trials, small samples, and poor methodological quality of the trials limited their ability to draw firm conclusions.

Additional research is needed to fully understand the potential effects of probiotics on body weight and obesity in humans. Probiotics from foods or dietary supplements are safe in healthy people.

No serious adverse effects have been reported in clinical trials [ , ], and side effects are usually minor, consisting of gastrointestinal symptoms, such as gas [ ]. Pyruvate is a three-carbon compound that is generated in the body through glycolysis [ ]. Pyruvate is also available as a dietary supplement, frequently in the form of calcium pyruvate.

Researchers have suggested that pyruvate enhances exercise performance and reduces body weight and body fat, possibly by increasing lipolysis and energy expenditure [ 6 , , ]. Only a few studies have examined the effects of pyruvate supplementation in humans. Although some of these studies suggest that pyruvate decreases body weight and body fat, others do not. At the end of the trial, the pyruvate group had significant decreases in body weight mean loss of 1. In the placebo group, these measurements did not change significantly compared to baseline.

However, a double-blind, placebo-controlled trial in 23 overweight women mean BMI The authors of a systematic review and meta-analysis of 6 randomized controlled trials in a total of participants concluded that 5—30 g pyruvate for 3—6 weeks reduces body weight by a mean of 0. However, the authors noted that the methodological quality of all trials is weak, preventing them from drawing firm conclusions. The safety of pyruvate has not been rigorously studied. Additional research is needed to better understand the safety and possible side effects of this compound.

Raspberry ketone is the primary aroma compound found in red raspberries Rubus idaeus , and it is added to some foods as a flavoring agent [ 16 , ]. In vitro and animal studies suggest that raspberry ketone might help prevent weight gain by increasing fatty acid oxidation, suppressing lipid accumulation, and inhibiting pancreatic lipase activity [ 16 ].

Although it has been touted on the Internet and national television as an effective way to burn fat, little evidence exists to support this claim. In mice fed a high-fat diet, raspberry ketone supplementation reduced food intake and body weight compared to the same diet without raspberry ketone [ ].

Only one randomized controlled trial has examined the effects of a dietary supplement containing raspberry ketone on weight loss. This product contained 2, mg of a proprietary blend of raspberry ketone, caffeine, bitter orange, ginger, garlic, cayenne, L-theanine, and pepper extract along with B- vitamins and chromium. During the 8-week study, participants followed a calorie-restricted diet approximately calories less per day than estimated needs and engaged in moderate exercise 60 minutes 3 days per week.

However, 25 of the 70 participants dropped out of the study, and results were reported for only the 45 participants who completed the study i. Furthermore, the product contained many ingredients in addition to raspberry ketone, making it impossible to determine the effects of raspberry ketone alone.

Typical diets provide only a few mg of raspberry ketones a day. Doses contained in dietary supplements typically range from to 1, mg, and the safety of such doses has never been evaluated in humans [ ]. However, additional research on raspberry ketone is needed to better understand its safety and side effects.

Vitamin D, which is fat soluble, is present in a few foods, such as fatty fish, cheese, egg yolks, and vitamin D-fortified milk. It is also available in many dietary supplements, and humans synthesize it naturally when their skin is exposed to sunlight.

Vitamin D promotes calcium absorption in the gastrointestinal tract and is needed for proper bone growth and remodeling [ 56 ]. Observational studies indicate that greater body weights are associated with lower vitamin D status, and obese individuals frequently have marginal or deficient circulating levels of vitamin D [ ]. Nevertheless, the association between vitamin D and obesity raises the question of whether increasing vitamin D concentrations might reduce body weight [ , ].

Despite the association between low vitamin D levels and obesity, scientific evidence does not support a cause-and-effect relationship. The authors commented that the cause of this finding might have been stored vitamin D in body fat and skeletal muscle that was released during weight loss. However, according to a meta-analysis of 12 vitamin D supplementation trials including 5 in which body composition measurements were primary outcomes , vitamin D supplements without calorie restriction did not affect body weight or fat mass compared to placebo [ ].

Overall, the available research suggests that consuming higher amounts of vitamin D or taking vitamin D supplements does not promote weight loss. Vitamin D toxicity can cause anorexia, weight loss, polyuria, and heart arrhythmias. It can also raise calcium blood levels, which can cause vascular and tissue calcification. White kidney bean or bean pod Phaseolus vulgaris is a legume that is native to Mexico, Central America, and South America and is cultivated worldwide [ ].

Phaseolus vulgaris extract is an ingredient in some weight-loss dietary supplements marketed as carbohydrate- or starch-absorption "blockers. Phaseolus vulgaris might also act as an appetite suppressant [ , ]. The effect of Phaseolus vulgaris on weight loss and body fat has been examined in a few clinical trials, which had inconsistent results. After 30 days, those receiving Phaseolus vulgaris extract lost significantly more weight mean weight loss 2. Those in the Phaseolus vulgaris group also experienced a significantly greater reduction in fat mass, adipose tissue thickness, and waist—hip—thigh circumference.

However, the authors noted that the quality of the trials included in their review was poor, making it impossible to draw firm conclusions.

After the publication of that review, a week clinical trial in overweight and obese men and women showed that Phaseolus vulgaris modestly yet significantly reduced body weight and body fat [ ]. Compared to those taking placebo, those receiving Phaseolus vulgaris lost significantly more body weight mean loss of 2. Reported adverse effects for Phaseolus vulgaris are minor and include headaches, soft stools, flatulence, and constipation [ ].

No serious adverse effects of Phaseolus vulgaris have been reported in clinical trials, but no trials have lasted longer than 13 weeks. Yerba Maté see section on caffeine above. Yohimbe Pausinystalia yohimbe, Pausinystalia johimbe is a West African evergreen tree. Yohimbine has hyperadrenergic physiological effects because it acts as an alpha-2 receptor antagonist [ 6 , ]. Yohimbe extract is an ingredient in some dietary supplements that are promoted for libido enhancement, body building, and weight loss [ ], but it is used primarily as a traditional remedy for sexual dysfunction in men.

The authors of a review of yohimbe concluded that no conclusive evidence indicates that yohimbe affects body weight or body mass [ ]. The author of a review of yohimbe reached similar conclusions, noting that results from small human trials of yohimbine for weight loss are contradictory and the evidence base is insufficient to support a weight loss claim for this compound [ ].

Yohimbe can be dangerous. Taking 20 to 40 mg of yohimbine has been reported to increase blood pressure slightly, whereas doses of mg or higher can cause headaches, hypertension, anxiety, agitation, tachycardia, myocardial infarction, cardiac failure, and death [ 43 , , , , ]. More recently, dietary supplements containing yohimbe accounted for 1, self-reports to U.

Although yohimbe is generally well tolerated at low doses [ ], no safe dose has been established for it. Yohimbe should only be used under medical supervision because of its potential to produce serious adverse effects [ ]. Ephedra sinica, Ephedra equisentina, and Ephedra intermedia [ ]. The active compounds, which are in the plant's stem and account for about 1.

In the s, ephedra—frequently combined with caffeine—was a popular ingredient in dietary supplements sold for weight loss and to enhance athletic performance. The FDA no longer permits the use of ephedra in dietary supplements because of safety concerns that are detailed below, but information is provided here in response to continued interest in this ingredient. Ephedrine acts as a stimulant in the central nervous system [ , ], and it might increase thermogenesis and act as an appetite suppressant [ ].

The authors of a meta- analysis that included 20 clinical trials concluded that ephedrine and ephedra are modestly effective for short-term weight loss 6 months or less , but no studies have assessed their long-term effects [ ].

GNC Lean Shakes Flavors and Taste