Fat burners are probably the fastest growing supplement category in the bodybuilding world.
In the past, supplement manufacturers have focused on making products to help you get bigger. The most popular products in your average supplement store are still weight gainers and protein shakes. The first thing most people want to do when they start to train is get bigger. Thanks to the ubiquity of weight gainers and the abundance of calorie-dense foods, we now find it very easy to put weight on. Too easy, in fact.
This is why fat burners are quickly becoming some of the most widely used and highly praised supplements in the world. For most guys, it’s easy getting big. You just lift heavy and eat like a horse. What’s not so easy is getting ripped. It requires hard work and extreme discipline.
It’s not surprising then tat the number of fat burners on the market has ballooned over the last 5 years. As it stands, there are literally hundreds of products on the market right now offering accelerated fat loss, better appetite control, and more.
Many of these supplements come and go; they are popular for a few years, but eventually people learn that they don’t do a great deal for them. Others stick around; their effectiveness earns them a loyal following, and they continue to sell well in what is an increasingly crowded market.
But for the average user, it is practically impossible to tell which supplements offer value and which don’t.
To put it more bluntly, it’s really hard to tell the good fat burners from the crap.
The manufacturers certainly don’t help.
They pile on the hyperbole like there’s no tomorrow. Everybody claims that their supplement is the “most powerful and effective on the market”.
They all claim to have “unique formulas”.
Of course they’ve all been “painstakingly formulated”, with ingredients chosen for their “scientifically proven effects”.
If you read each supplement’s sales page, you’ll see that they all promise to give you results that can’t be found elsewhere.
But obviously, most of these manufacturers must be lying.
Not every supplement can be the best.
They can’t all have unique formulas.
By definition, they can’t all offer market-beating value.
We think the manufacturers know this full well; they just don’t mind heaping on the sales speak and the lies to get you to spend your hard-earned cash.
So how can you reliably cut through the noise and separate the good fat burners from the over-priced, ineffective crap?
We think the only way to do this is to completely ignore what the manufacturers say and look at the formulas themselves. By examining each ingredient one by one and seeing what the latest scientific studies really have to say about them, you can get a good idea for what works and what doesn’t.
To help you on your way, we’ve created this list! Below, you will find an overview of the studies relating to the most widely used ingredients fat burners right now.
In each case, we’ve taken an impartial look at what the empirical evidence says and come up with a final verdict. Some of these ingredients are legit; the research has found them to be effective and reliable in humans. Others are bogus; the only thing backing them up is hype.
If you know of a substance that you think we should feature, please let us know in the comments section at the end.
Green Coffee Bean Extract – LEGIT
- In this paper, researchers looked at a number of published, peer-reviewed clinical trials which looked at green coffee bean extract’s ability to enhance fat loss. They eventually found three studies which met their criteria, all of which seemed to show GCBE having a positive effect on body fat levels: “The evidence from RCTs seems to indicate that the intake of GCE can promote weight loss.” However, the researchers posed several important caveats to this conclusion: “The size of the effect is small, and the clinical relevance of this effect is uncertain. More rigorous trials with longer duration are needed to assess the efficacy and safety of GCE as a weight loss supplement.” (Published 2011 in Gatroenterology Research & Practice).
- A really fascinating study conducted on mice makes the case for green coffee bean extract as a fat burner. In this clinical investigation, researchers gave mice a GCBE for 13 days and measured the effect on body composition. The extract mainly chlorogenic acid and caffeine. The findings of this study are quite conclusive: “It was found that 0.5% and 1% GCBE reduced visceral fat content and body weight. Caffeine and chlorogenic acid showed a tendency to reduce visceral fat and body weight…These results suggest that GCBE is possibly effective against weight gain and fat accumulation by inhibition of fat absorption and activation of fat metabolism in the liver. Caffeine was found to be a suppressor of fat absorption, while chlorogenic acid was found to be partially involved in the suppressive effect of GCBE that resulted in the reduction of hepatic TG level.” (Published 2006 in BMC Complimentary & Alternative Medicine).
- Another study looked specifically at chlorogenic acid and its ability to reduce body fat in obese mice. The findings are really interesting, and are worth quoting at length: ” Both caffeic acid and chlorogenic acid significantly lowered body weight, visceral fat mass and plasma leptin and insulin levels compared to the high-fat control group. They also lowered triglyceride (in plasma, liver and heart) and cholesterol (in plasma, adipose tissue and heart) concentrations. Triglyceride content in adipose tissue was significantly lowered, whereas the plasma adiponectin level was elevated by chlorogenic acid supplementation compared to the high-fat control group…These results suggest that caffeic acid and chlorogenic acid improve body weight, lipid metabolism and obesity-related hormones levels in high-fat fed mice. Chlorogenic acid seemed to be more potent for body weight reduction and regulation of lipid metabolism than caffeic acid.” (Published 2010 in Food and Chemical Toxicology).
One thing emerges from these studies and others; it is clear that while chlorogenic acid has a fat burning effect by itself, it works significantly better when used in conjunction with caffeine. The exact mechanism of action is not made clear by these studies. The most convincing theory is that it helps your body process and regulate glucose. We think this is probably the main way that GCBE – or rather chlorogenic acid – helps accelerate fat loss. However, more research is definitely needed.
Another thing becomes clear when you read the available studies on GCBE; the effect it has on body fat levels is quite small. It is statistically significant, but it is definitely small.
While Green Coffee Bean Extract has a place in a well-balanced fat burner, it isn’t really going to make a huge difference when used alone. Standalone GCBE supplements are probably going to give you disappointing results. It should be used alongside caffeine and other, complimentary fat burning substances.
Caffeine – LEGIT
- If you’re looking for evidence of caffeine’s efficacy as a fat burner, then you will inevitably come across this widely-cited study. This is easily one of the most discussed studies relating to caffeine and its use as a fat burner. There’s no point in us just rambling about it; the researchers themselves do a much better job of explaining the study and their findings: “Mature male rats (average weight of 442 g) were assigned to four grouping combinations of the two treatment variables: caffeine ingestion (caf, no caf) and exercise training (ex, sed). Two groups trained by swimming 90 min, 5 d/wk (caf-ex, no caf-ex) while two groups served as untrained controls (caf-sed, no caf-sed). Forty-five minutes prior to swimming, doses of saline only or of caffeine dissolved in saline (5 mg caffeine/kg body weight) were administered to the no caffeine and caffeine groups, respectively. After 9 wk of training, body weight and epididymal and retroperitoneal fat-pad weights were significantly reduced in the caffeine groups and in the exercise groups (P less than 0.05). Epididymal fat-cell size was significantly reduced by caffeine treatment, and exercise training reduced fat-cell diameters in both epididymal and retroperitoneal fat-pads (P less than 0.05). The additional 22% reduction in body weight, 25% reduction in epididymal fat-cell size, and 5 and 6% reductions in epididymal and retroperitoneal fat-pad weights, respectively, in the caf-ex group beyond the no caf-ex group support the hypothesis that fat loss with aerobic exercise can be increased when caffeine is ingested prior to the training sessions.” (Published 1982 in Medicine and Science in Sports and Exercise).
- Other robust studies have since corroborated the findings of this animal study and shown that the effects occur in humans too. This trial, for example, looked at how caffeine consumption correlated with body fat levels. The results are quite clear: “High caffeine intake was associated with weight loss through thermogenesis and fat oxidation and with suppressed leptin in women. In habitual low caffeine consumers, the green tea‐caffeine mixture improved WM, partly through thermogenesis and fat oxidation.” (Published 2012 in Obesity).
We could keep on citing study after study showing that caffeine consumption is closely correlated with lower body fat levels, but we think these two studies are sufficient to start off your own research. There are a few important points that need to be made, however.
If you read the studies on caffeine as a fat burner, you will note that it does seem to have a direct effect on fat oxidation. One of the studies cited above explicitly mentions thermogenesis as an explanation for caffeine’s fat burning power. Indeed, caffeine consumption is positively correlated with lower body fat levels independent of exercise and other potentially confounding factors.
However, the direct effect that caffeine has on fat oxidation is just half the story.
Caffeine’s main benefit is the fact that it increases physical energy levels while simultaneously decreasing appetite. The reason why this is a benefit should be obvious; being able to get through your workouts despite being in a caloric deficit, and then not being too hungry afterwards, will make your cut very easy.
- This paper does a very good job of summarizing caffeine’s performance enhancing effects. People have known that caffeine is a natural stimulant for centuries. But few people really appreciate how effective it is as an all-round performance enhancer. As you’ll see if you read the paper, caffeine increases physical energy, various aspects of cognitive performance, and directly accelerates fat oxidation. You can’t ask for much more than that!
Caffeine is much more than just an energy kicker. It is a fat burner in and of itself. Robust, conclusive studies have shown that it directly increases fat oxidation independently of exercise. However, that it not to say that the increased energy you get form caffeine is a small benefit. Not at all. The extra energy that caffeine gives you is VITAL if you are going to maintain your training intensity during a serious cut.
There’s no two ways about it – all good fat burners should contain a healthy dose of high quality, purified caffeine.
Garcinia Cambogia – BOGUS
- A good place to start an analysis of Garcinia Cambogia is this excellent, wide-ranging paper. The researchers note that Garcinia seems to be very safe and well tolerated. They note that several studies have found it to be an effective complimentary treatment for weight loss. But they then go on to provide quite a resounding conclusion which, for us, defines this commonly used ingredient: “However, definitive conclusions that Garcinia/HCA supplements are efficient tools against various health problems especially obesity remain to be proven in larger-scale and longer-term clinical trials, despite substantial public interest in such supplements. Many diet supplements containing Garcinia/HCA marketed as weight management products are the combination of active ingredients rather than containing a single agent. Thus it is difficult to evaluate the effectiveness of single agents when the combination products are tested.” (Published 2013 in Evidence Based Complimentary & Alternative Medicine).
- Another study, which you can find here, came to very similar conclusions. As in the first study, the researchers began by noting that Garcinia Cambogia – or rather a particular compound found in Garcinia Cambogia – is sold around the world as a weight loss aid. However, they are not swayed by the available evidence. Their conclusion reads as follows: “Gastrointestinal adverse events were twice as common in the HCA group compared with placebo in one included study. It is concluded that the RCTs suggest that Garcinia extracts/HCA can cause short-term weight loss. The magnitude of the effect is small, and the clinical relevance is uncertain. Future trials should be more rigorous and better reported.” (Published 2011 in the Journal of Obesity).
- There are lots of studies showing that Garcinia Cambogia has no notable effect on fat loss in humans. This trial took obese but otherwise healthy adults and gave them a large dose (3g) of Garcinia Cambogia for 12 weeks. The conclusion pulls no punches: “Garcinia cambogia failed to produce significant weight loss and fat mass loss beyond that observed with placebo.” (Published 1998 in JAMA).
The evidence really is overwhelming here. We have only cited one trial conducted on humans, but there are plenty out there. The few that seem to show Garcinia having a significant effect on fat loss are completely outnumbered. What’s more, these studies are often poorly designed, short-term, and the results very meager.
There is one more study that we really need to address before moving on.
- You will often see this trial being cited in support of the use of Garcinia Cambogia as a fat burner. Manufacturers claim this paper backs up their claims; that it describes Garcinia as an appetite suppressant and fat oxidizer. The problem is, IT DOESN’T! Here is what the researchers found: “An efficacious dosage of HCA-SX (4500 mg/day t.i.d.) provides a good source of Ca2+ (495 mg, 49.5% of RDI) and K+ (720 mg, 15% of RDI). Ca2+ ions are involved in weight management by increasing lipid metabolism, enhancing thermogenesis, and increasing bone density. K+, on the other hand, increases energy, reduces hypertension, increases muscle strength and regulates arrhythmias.” The researchers go on to say that this exact compound of hydroxycitricacid has been shown to reduce appetite and burn fat. But we have never seen any convincing evidence of this effect in humans.
We think that this is ‘case closed’ for Garcinia Cambogia. We understand why supplement manufacturers are so adamant on using it; it’s cheap, there’s lots of it being made, and there is some evidence which can be twisted and turned into proof of efficacy.
But when you really look at the science, it’s quite clear that Garcinia Cambogia does not work.
Glucomannan – LEGIT
- When people are discussing glucomannan and is usefulness as a fat burner, they will usually start with this study. Here, researchers gave participants either 1.3g of glucomannan or an identical placebo, which they took three times daily before meals with water. The study lasted for 8 weeks. The findings were not very encouraging: “At 8 weeks, there was no significant difference between the glucomannan and placebo groups in amount of weight loss (−.40 ± .06 and −.43 ± .07, resp.) or other efficacy outcomes or in any of the safety outcomes. Conclusions. Glucomannan supplements administered over 8 weeks were well tolerated but did not promote weight loss or significantly alter body composition, hunger/fullness, or lipid and glucose parameters.” (Published 2013 in the Journal of Obesity). The researchers did note that people consuming glucomannan were significantly more full than the placebo group (12% vs 3%), but the effect only lasted for a few hours.
So while the study failed to affect total weight loss, it did increase the feeling of fullness during and after each meal. Had the participants been trying to cut back on food, they probably would have benefited a lot more from the glucomannan. They were not trying to restrict their diet or anything like that.
However, other studies have found that glucomannan supplementation enhances fat loss.
- This study investigated how a glucomannan-enriched diet influenced body composition in isolation and in conjunction with exercise. The results are worth repeating here in full: “In addition, exercise appeared to augment the reduction in fat mass (by 63% and 50%; men and women, respectively) and waist circumference, but did not affect total weight loss. Addition of a resistance and endurance exercise training program to a glucomannan diet regimen significantly improved measures of body composition, HDL-C, and TC/HDL-C ratio.” (Published 2007 in Metabolism).
- This clinical trial found that supplementing with glucomannan led to significantly greater weight loss compared to control. Interestingly, the researchers also found that the glucomannan-treated participants had improved cholesterol profiles after the 8 weeks were over. They were using 500mg of glucomannan, taken twice daily. The researchers report no adverse reactions. (Published 1984 in the International Journal of Obesity).
In our opinion, every high quality fat burner needs to contain some kind of appetite support. We don’t want something that’s going to completely kill your appetite, and we don’t want anything that will block the absorption of nutrients. If you want to look good and stay healthy, you need to eat well. However, we do need something to help us avoid over-eating. By making you feel fuller after meals, glucomannan can help you get through the worst parts of your diet, which means an ultimately more successful cut.
Some trials have used very large quantities of glucomannan. We think this tends to cause side effects (e.g excessive bloating). Some studies have seen good results using 1g or less consumed around meal times.
Learn more from our in-depth fat burner buyers guide.
Check out our list of the best fat burners in the UK.