Do Fat Burners Work?

Pills might sound like a gimmick, but the evidence for increased fat oxidation pretty interesting — if you know what to expect.

Expert Verified By: Aastha Kalra, MD

Fat burners do burn fat.

But maybe not in quite the same way as you think.

Here we’re answering one of the most controversial questions in supplements: do fat burners even do anything?

To answer in short: a lot of evidence does suggest that certain compounds in popular “fat burning” supplements increase the amount of fat you burn for fuel. Generally speaking, we either burn fatty acids or glucose (stored carbohydrates) for energy and while increasing fat oxidation is more reliably accomplished with a healthy sleep habit and regular exercise, ingredients found in places like green tea and coffee may help as well.(1)

To thoroughly understand these supplements, we’ve looked at dozens of studies and enlisted the help of a weight loss-focused physician to learn what you should know about these topics:

  1. Green Tea Extract
  2. Caffeine
  3. Capsaicin
  4. Appetite Suppressants

Editor’s note: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems.

[Looking for the most effective product? Don’t miss our list of the 5 best fat burners on the market!]

green tea cup

Green Tea Extract

In green tea there’s a catechin, a kind of antioxidant, called Epigallocatechin gallate, or EGCG. It’s one of the most popular ingredients in fat burner supplements because studies reliably show an effect on fat oxidation.(2) About half a gram of EGCG per day has been linked to an increase in anywhere from 4% to 17% to 33% in the amount of fat you burn for fuel. (3)(4)(5)

That’s a big range.

“In another study published in 2016, which was a randomized controlled trial, researchers used up to 850 milligrams of EGCG — the equivalent of about a dozen cups of green tea — and found the subjects lowered their bodyweight by twelve kilograms over twelve weeks,”

says Dr. Aastha Kalra, a New York-based physician who specializes in weight loss.(6) “It was also shown that the catechins reduced ghrelin, a hunger hormone.”

 That’s an extraordinarily fast rate of weight loss, although it’s worth pointing out that this trial was performed on 115 obese women, and obese people tend to lose weight more quickly than those who are already lean. Plenty of other studies found more modest weight loss, but there still seems to be some merit in experimenting with EGCG provided it’s part of a robust weight loss plan that includes closely monitoring calories.(7)(8)

coffee cup


The fat oxidation effect of EGCG appears to be stronger when it’s combined with caffeine, which on its own is probably the most widely used fat burner on Earth — though many are unaware of its potential impact on fat oxidation. Some studies have suggested it can temporarily double the turnover of lipids, which in turn leads to increased fat oxidation.(9)(10)

“Caffeine can help metabolize fat from fatty tissues,” says Dr. Kalra. “It does so by increasing blood levels of a hormone called epinephrine, also called adrenaline, which travels through the blood to fatty tissues creating these signals to break down fat.”

There’s also evidence caffeine helps you to burn more calories. Some studies suggest that one to two hundred milligrams a day — a short cup of Starbucks® coffee has about 160 milligrams — could temporarily produce between 3 and 11 percent more calories burned.(11)(12) For most people that’s in the area of 50 to 200 calories.

“The fat oxidation result is even more prominent in individuals who are already lean,” adds Dr. Kalra. “There’s a very interesting  study that showed caffeine increased fat burning by as much as 29 percent in lean individuals while the increase was about 10 percent in individuals that were obese.”(13)

The effect is also more pronounced in younger individuals, but there’s a caveat: people become tolerant to the effects over time.(14) So in the short term caffeine can boost metabolic rate and help with fat burning, but it may not the most sustainable or reliable impact.

[Take a closer look at all the ways caffeine affects your metabolism in our guide to caffeine and weight loss.]

chili peppers


The other main, very popular fat burning ingredient that should be addressed is capsaicin, the main component in chili peppers that makes them spicy. It’s perhaps best known for increasing the amount of calories you burn, but the effect on fat oxidation bears a mention as well.

A 2007 study published in the Journal of Nutritional Science and Vitaminology found that participants who ate 150 milligrams of capsaicin an hour before working out experienced about 40 percent more fat oxidation when compared to a placebo.(15) Other studies found an effect with doses even as low as 2.5 milligrams, which one study found produced 10 percent more fat oxidation in the day following ingestion.(16)(17)(18)(19The effect seems to be similar to that of caffeine, in that capsaicin is tied to a boost in adrenaline.(20)

Like caffeine, though, it seems that you can easily build a tolerance to these effects, so supplements may be the most useful for folks who don’t already eat a lot of spicy food.(21)(22)

 [But does capsaicin help you burn more calories? Read our complete guide to cayenne pepper and weight loss.]

Credit: Salix, Licensed under Creative Commons 2.0.

Appetite Suppressants

If we’re strictly talking about fat oxidation and not the potential effects on appetite, these effects are temporary and ultimately pretty small. They may make a difference if you’re already very lean and trying to rid yourself of one or two final percentage points of body fat.

Even in those cases, the difference won’t matter unless you’re tracking your calories. That’s why, if you’re trying to lose weight, perhaps the most useful ingredients in a fat burner aren’t the ones that help you burn fat, they’re the ones that help you to eat less.

Cayenne might lower appetite, though the effect is a bit more disputed with green tea and caffeine.(17)(23)(24) Here are some of the more interesting ingredients that might do a better job in this area.


A gram of that a day may reduce appetite because it’s made from a type of fiber that expands in the belly.(25)(26) Some studies dispute that, but it’s worth thinking about — it’s the main ingredient in Leanbean and Instant Knockout, which we’ve found to be quite effective products.(27)

psyllium husk

Psyllium Husk

Made from the seeds of the Plantago plant, one teaspoon contains a whopping five grams of fiber, about twenty percent of the daily intake. One or two teaspoons before a meal seems to help with appetite control, not to mention the links psyllium husk (and fiber intake in general) have with reduced risks of diabetes and heart disease. (28)(29)

[Learn more about the surprising benefits of fiber for your health in our article on digestive health.]


This is the last appetite suppressant we want to mention. It’s made from the plant Griffonia simplicifolia, and it’s considered a serotonin precursor, so it might increase the levels of this hormone that’s related to satiety.(30) That means, according to some research, it may reduce cravings to eat more by making you more content with what you’ve eaten.(31)

fat loss man

The Takeaway

So do fat burners work?

The best way to lose weight is to track your calories and if you’re doing that, fat burners will be more effective: they might shave off an extra 100ish calories from your daily burn, they might slightly increase how much of that comes from fat, and they might make it easier to stick to a lower calorie intake if they suppress your appetite.

Don’t think of these pills as magic. Think of them as supplements to a more complete and robust weight loss plan. And if you are looking for a robust weight loss plan, talk to your doctor or a dietitian. Weight loss is tough; it’s good to have some help.


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