What it is: The compound that gives hot peppers their kick.
How it works: Although the weight-loss benefits of the compound in pill form have not been confirmed, eating fresh chilies or ground red pepper (including cayenne) could turn on your body’s fight-or-flight response. “Because your body perceives that it’s under stress, it burns more calories,” says Mary-Jon Ludy, an assistant professor of clinical nutrition at Bowling Green State University, in Bowling Green, Ohio. It’s no bonfire, but you might burn about 10 more calories after eating a meal that contains capsaicin than after eating a meal that doesn’t—and eat about 50 fewer at your following meal.
Good to know: As little as one-quarter teaspoon of red pepper may do the trick at first. But if you consume the hot stuff regularly, you might need greater amounts to get you going, says Ludy.
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What it is: Green tea is a minimally processed tea that contains high concentrations of a plant antioxidant called epigallocatechin gallate, or EGCG, which may help with weight loss.
How it works: “EGCG blocks the body’s ability to digest fat,” says Josh Lambert, an associate professor of food science at Pennsylvania State University, in University Park. The caffeine in green tea may help trim you down, too: A 2011 synopsis of studies published in the journal Obesity Reviews found that people who consumed at least two cups a day of caffeinated green tea lost three pounds in 12 weeks without changing their diets.
Good to know: Steep tea for two to five minutes and drink two or more cups a day to reap the weight-loss benefits. If the caffeine disturbs your sleep (green tea packs 24 to 40 milligrams per eight ounces, or about a quarter of the amount found in most coffee), consume the last cup at least four hours before bedtime, says Jeffrey Blumberg, Ph.D., the director of the Antioxidants Research Laboratory at Tufts University, in Boston.
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What it is: Edible fiber from the root of the Asian konjac plant, available in capsules, powder form, and shirataki noodles (traditional Japanese noodles similar to udon in texture). It’s a condensed form of fiber, swelling up to 17 times its volume in water.
How it works: More than any other type of fiber, it may help you drop pounds by making you feel satisfied after eating and by allowing food to be eliminated before it has a chance to be absorbed, says registered dietitian David Grotto, the author of The Best Things You Can Eat ($16, amazon.com).
Good to know: You may prefer the pills to the noodles, which can be gummy. You’ll need about one to five grams a day, and the fiber may be most powerful when combined with exercise: Overweight women who took glucomannan and exercised for an hour three times a week lost 50 percent more fat than did women who supplemented with glucomannan but didn’t exercise, according to a 2007 study from the journal Metabolism.
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Alpha Lipoic Acid
What it is: A fatty acid found in red meats and organ meats.
How it works: This antioxidant reduces inflammation and can help you lose weight. In a 2011 study published in The American Journal of Medicine, obese people who were told to reduce their food intake prior to the study by 600 calories a day and who took 1,800 milligrams of alpha lipoic acid daily for 20 weeks lost significantly more weight—up to 5 percent of their total body weight—than did a placebo group.
Good to know: While it’s generally best to get nutrients from foods, supplements win out in this case, since the foods most laden with alpha lipoic acid—red and organ meats—are also packed with saturated fat and cholesterol. Take anywhere from 1,200 to 1,800 milligrams a day.
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What it is: The only over-the-counter weight-loss supplement approved by the U.S. Food and Drug Administration.
How it works: The active ingredient, orlistat, blocks an enzyme that breaks down fat in the gut, preventing about 25 percent of fat calories from being absorbed. So with Alli you can lose 20 to 50 percent more weight than with diet and exercise alone. “Results aren’t dramatic, but it can help,” says Caroline Apovian, M.D., director of the Nutrition and Weight Management Center at Boston University Medical Center.
Good to know: Alli can block the absorption of important fat-soluble vitamins, like vitamins A, D, E, and K, so take those supplements two hours before or after taking Alli.