By Linnea Zielinski
You're not alone if the promises on fat burner bottles have tempted you. Especially if you've struggled to lose fat, you've probably at least thought, "Do fat burners work?" while reading up on supplements. Sexy phrases like “boosts metabolism" and “promotes fat loss" can get you to buy before you've thought it through.
But this may not be a harmless decision. Certain fat burners can come with potential side effects and dangers. And if they don't work, you're flushing your hard-earned money without moving closer to your goals. Before you buy, here's what you need to know about these products' risks and limitations — and why you may not need them to lean out successfully.
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Most active ingredients in over-the-counter fat loss supplements are chosen because they support two different processes:
“There are no standard ingredients in fat burners," explains Brianna Johnson-Rabbett, MD, Assistant Professor UNMC/Nebraska Medicine, who is board-certified in Endocrinology, Diabetes and Metabolism and is a Diplomate of the American Board of Obesity Medicine. However, ingredients you'll commonly see on the labels of fat burners include the following:
Chances are you're familiar with this one. Caffeine is one ingredient in fat burners with some favorable research behind it. You won't always see “caffeine" on the label of fat-loss supplements, though. It can also go by green tea extract, green coffee bean extract, or guarana, to name a few.
Capsaicin is the compound in hot peppers that gives them their kick. You may also see it listed on labels as capsicum, the name of the group of plants to which fiery peppers belong.
Chromium is a lesser-known mineral that occurs naturally in foods like fruits, vegetables, meats, and grains. There are studies that show that chromium may help aid insulin action, although human studies are inconclusive.
There are a lot of claims about CLA, a fatty acid found in meat and dairy products. There are claims that it can help lower how much you eat, decrease fat production in your body, and increase the breakdown of fat — but a vast majority of studies have been conducted on animals, not people.
Forskolin naturally occurs in plants, and studies have found that it can help increase the breakdown of fat. As promising as that sounds, most studies on this ingredient have been done on cell samples or in rats.
Garcinia cambogia is a plant from Southeast Asia, but it's a chemical in the pulp that has been studied for its weight loss potential. Research hasn't shown it to be effective.
Glucomannan is a water-soluble fiber taken from konjac roots (the same root used to make shirataki noodles and konjac jelly). Although increasing fiber intake can help you feel fuller for longer, studies haven't confirmed that glucomannan helps with fat loss.
L-carnitine is naturally found in meat and dairy products and has been claimed to help you lose weight, lean out, and retain muscle mass. It also plays a crucial role in how our bodies metabolize fat.
Raspberries naturally produce ketones, compounds said to help weight loss, but most raspberry ketones are manufactured. Most research on these compounds has been done on animals, and there are concerns over their safety in high concentrations.
Yohimbe is a type of tree native to central and western Africa, and yohimbine is a compound found in its bark. Yohimbine is said to help with a long list of health conditions and aid weight loss, but research hasn't been conclusive regarding these claims.
Unfortunately, there are many reasons why many of these products tend to let people down. Some people may believe that taking a fat burner alone is enough to cause weight loss, but that just isn't the case. You need to create a calorie deficit — through diet, exercise, or a combination of the two — to see any benefit from these supplements.
When you dig into the studies, you find that research on fat loss supplement ingredients is limited. “There are few studies supporting the use of any of these substances," explains Johnson-Rabbett, “and usually there are significant issues with the studies that are available." The research doesn't look at enough people or structure their experiments well enough to draw reliable conclusions about how these ingredients help with weight or fat loss.
These products may also use amounts of these ingredients that are far too low to effect any change.
Caffeine has been associated with fat loss — but it still has to be paired with a solid diet and exercise plan. If you've had one too many cups of coffee, you know from experience that there's a limit to how much you can take.
Consuming too much caffeine can cause unpleasant side effects and may be dangerous. Up to 400 mg should be safe for healthy adults, but that's total intake. This total needs to include all caffeinated beverages, supplements with caffeine, and foods with caffeine content like chocolate.*
Be mindful of how much is too much caffeine for you, and talk to your doctor since they can advise you on what's safe to take given your individual state of health.
“I suspect fat burners are popular because losing weight can be very difficult," says Johnson-Rabbett. “Taking an over-the-counter supplement seems like a safe and easy way to potentially help with weight loss." She adds that it's important to proceed with caution. The potential benefits are written right there on the packaging, but unfortunately, the potential risks are not. People buying fat burners may have no idea they can come with possible side effects and dangers.
The common side effects can be unpleasant, but there are also real dangers to taking fat burners without consulting your doctor. If your fat loss supplement overloads your caffeine intake, you may feel nauseous and jittery. But these products can also interact negatively with medications you may be taking, which isn't a risk worth taking.
“We can lose fat by changing our dietary patterns to decrease calorie consumption and by exercising," says Johnson-Rabbett. You probably already know these basics, but they're not as flashy and attractive as the promises made by these fat-loss supplements.
It's important to remember that fat loss takes time, and you can't choose where your body loses fat first. That means it can take quite a while sticking to a diet and exercise plan.
If staying committed to a calorie deficit is difficult for you, some strategies may make it easier. “Most people can benefit from significant increases in the amount of non-starchy vegetables they eat and choosing leaner protein options," Johnson-Rabbett explains. These foods take up more space in your stomach and help you feel fuller for longer, which can keep cravings and snacking at bay.
Exercise is another tool in your arsenal for creating an overall calorie deficit. Every trainer has his or her own favorite type of workout for burning fat and promoting weight loss, but the reality is that the best one for you is the one that motivates and challenges you. "When you enjoy exercise, you're more likely to do it consistently, and consistency is what produces results," says Trevor Thieme, CSCS, LADDER's senior director of fitness and nutrition content.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.