June 26, 2014 5:53 AM EDT

If there existed a safe, effective and rigorously tested weight-loss pill that could help slim you down without dangerous side effects, you’d be best off hearing about it from your doctor. But for now, most weight-loss supplements are not evaluated for safety by the U.S. Food and Drug Administration (FDA) and their too-good-to-be-true promises come from marketers, whose claims are facing scrutiny by the Federal Trade Commission. Diet-supplement claims were also at the center of a recent U.S. Senate hearing, where lawmakers questioned Dr. Mehmet Oz for having called some diet pills a “miracle” and “magic weight-loss cure” despite a lack of validated scientific evidence. And while prescription weight-loss drugs like Belviq and Qsymia are regulated by the FDA, supplements are not. A bill introduced in 2013 requiring companies to register their products with the FDA and improve labeling to include safety risks and efficacy is now before a Senate committee. In the meantime, here is what science says–or doesn’t say–about what’s out there.

The Universe of Diet Supplements

[The following text appears within a diagram. Please see your hard copy for actual diagram.]

GAMMA LINOLEIC ACID

DNP

FAT BURNERS

CLAIM: They will “melt away” fat and help build muscle

SCIENCE: Not much. There’s insufficient evidence that they can contribute to weight loss

RISKS: Some are banned by the FDA (though they remain available online) over risks of organ failure

AÇAI BERRY

WHEY

HOODIA.

BITTER ORANGE.

APPETITE

SUPPRESSANTS

CLAIM: The pills and powders can make you feel full, causing you to eat less

SCIENCE: There are few human studies confirming their effectiveness

RISKS: Since they haven’t been well studied, side effects are wholly unknown

GUAR GUM

HYDROXYCITRATE

FAT BLOCKERS

CLAIM: You won’t absorb as much dietary fat from your food

SCIENCE: There isn’t strong evidence that these work without a lower-calorie diet

RISKS: Some cause diarrhea and inhibit vitamin absorption, while others, made from shellfish, may trigger allergic reactions

CHITOSAN

LEPTIN

METABOLISM BOOSTERS

CLAIM: They help you burn more fat and calories

SCIENCE: Stimulants may help cells use more energy, but they can come with serious adverse effects

RISKS: Some stimulants speed heart rate and blood pressure, and heart attacks have been reported

BETA GLUCAN.

GREEN COFFEE.

This appears in the July 07, 2014 issue of TIME.

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