‘Fat burners’ are the most popular category of nutritional supplements. They claim to limit fat absorption, increase fat burning, increase energy output, and increase weight loss.
‘Fat burners’ do work - technically. Just not nearly to the degree that you might think.
Ingredients that promote fat burning are either sold alone or packaged as a blend and sold as ‘fat burners.’
Most ingredients included in 'fat burners' have no evidence backing up their effectiveness. Yet store shelves are overflowing with them.
This is because the rate at which new ingredients is introduced to the market by the industry constantly outpaces research and so many companies make outrageous claims about their 'fat-burners’. They greatly exaggerate the results that are possible by using these products, and use useless ingredients.
Your body burns fat stores as fuel only when metabolism outpaces food intake. In other words, when you are in a caloric deficit.
Metabolism slightly drops during the course of a fat loss diet and this can cause a plateau.
Depending on the ingredients, ’fat burners’ can help dieters by causing a very slight increase in metabolic rate and also suppress appetite. Both of which can help set fat loss in motion again. (I did some digging in the research and touched on those ingredients below.)
Do most people need to use ‘fat burners’ to lose fat? No.
The only folks who would really get anything out of using these products are the super lean bodybuilding and physique athletes looking to get stage-ready. And anyone who decides to use these has to use them in addition to diet and exercise. T
The effects of these supplements alone are pretty damn small. Therefore, these supplements will not help you get the results you want without proper nutrition and training.
Caffeine is often supplemented as a pre-workout due to its cognitive and performance benefits. It is also commonly added to ‘fat burners’ because caffeine consumption promotes thermogenesis.
One study showed that even a low dose of caffeine (100 mg or one cup of coffee) can increase resting metabolic rate in lean folks up to 3-4% and 5-8% with 200mg dosage . That’s about 50-100 calories for a 150-pound person. While other studies have reported that habitual consumption of 6 cups coffee (ie, 600 mg caffeine/day) causes an increase in energy expenditure of 100 calories/day.
Whatever the exact dosage is for each individual, caffeine's ability to enhance fat breakdown and slightly increase metabolism is well documented. Worth noting that caffeine is more powerful when consumed in an anhydrous state (in a capsule, tablet, or powder form) as compared to coffee.
Green Tea Extract
Green tea extract seems to have a positive effect on fat metabolism at rest and during exercises and appears to be a good fat loss agent. Green tea extract and caffeine have a potential synergistic effect.
In other words, green tea extract supplemented with caffeine has been shown to be more effective than either one alone. But these effects seem to be more pronounced in those people with a lower caffeine tolerance.
And just like caffeine, the effects of green tea extract on fat burning are relatively small. 12-week studies using dosages of ~50–300 mg/day of EGCG and ~0–100 mg/day caffeine have shown to result in up to three pounds or weight loss, with less habitual caffeine users seeing a larger effect.
Yes, those are wide ranges, but ideal dosing and timing has not been established.
Black Pepper and Cayenne Pepper
A common spice in many households is Black Pepper. While not a fat burner, piperine, a compound in black pepper increases the absorption of various drugs and supplements. For this reason, you will find it added to fat loss and weight loss products to potentially enhance absorption of the accompanying ingredients.
There is also some evidence showing that capsaicin, a compound in cayenne pepper, may help curb appetite increase thermogenesis. Ingestion of 150mg of capsaicin an hour before low-intensity exercise increases fat burning rates. This has been demonstrated in untrained healthy men.
Forskolin (Forskohlii extract)
Forskolin is produced by the Indian Coleus plant (Coleus forskohlii). In a 12-week long study with 30 obese men, forskolin has shown some promise. The researchers reported improved body composition, reduced fat mass, and body fat percentage with twice a day supplementation of 250mg of 10% forskolin extract. Although promising, there is limited human research on this ingredient.
Although we Canadians can't get our hands on Yohimbine, readers outside of Canada can benefit from this information.
Yohimbine supplementation makes body fat cells more susceptible to fat loss, is an effective fat burner for young and athletic people, and is said to help burn ‘stubborn fat’, like love handles.
Yohimbine may cause side effects such as anxiety symptoms and elevated heart rate. So, it’s definitely not for everyone. Yohimbine requires proper timing and dosage in relation to exercise and meals to be effective. Lyle Mcdonald has a more in-depth article regarding dosing and use.
 Dulloo, A. G., C. A. Geissler, T. Horton, A. Collins, and D. S. Miller. "Normal caffeine consumption: influence on thermogenesis and daily energy expenditure in lean and postobese human volunteers." The American journal of clinical nutrition 49, no. 1 (1989): 44-50.
 Goldstein, Erica R., Tim Ziegenfuss, Doug Kalman, Richard Kreider, Bill Campbell, Colin Wilborn, Lem Taylor et al. "International society of sports nutrition position stand: caffeine and performance." Journal of the International Society of Sports Nutrition 7, no. 1 (2010): 1.
 Godard, Michael P., Brad A. Johnson, and Scott R. Richmond. "Body composition and hormonal adaptations associated with forskolin consumption in overweight and obese men." Obesity Research 13, no. 8 (2005): 1335-1343.
 “Green Tea Catechins- Scientific Review on Usage, Dosage, Side Effects." Independent Analysis on Supplements & Nutrition. Accessed September 11, 2016. https://examine.com/supplements/Green+Tea+Catechins/.
 "Black Pepper - Scientific Review on Usage, Dosage, Side Effects." Independent Analysis on Supplements & Nutrition. Accessed September 11, 2016. https://examine.com/supplements/black-pepper/.
 Ludy, Mary-Jon, and Richard D. Mattes. "The effects of hedonically acceptable red pepper doses on thermogenesis and appetite." Physiology & behavior 102, no. 3 (2011): 251-258.
 Yohimbine - Scientific Review on Usage, Dosage, Side Effects." Independent Analysis on Supplements & Nutrition. Accessed September 11, 2016. https://examine.com/supplements/Yohimbine/.