The following may increase metabolism—but at a price, warns Walt Thompson, PhD, professor of kinesiology and health and nutrition at Georgia State University.
EPHEDRINE: Supplements containing ephedrine are still around, though they’ve been banned by the FDA. They dangerously speed up heart rate and raise blood pressure, increasing the risks of heart problems and stroke.
NICOTINE: It’s true that nicotine boosts metabolism. But those smokers may also be skinny because they have a form of emphysema, a disease that burns calories quickly—not in a good way.
CAFFEINE: Studies have shown that coffee may rev up metabolism, but the effect lasts less than 30 minutes. You’d have to drink gallons to have a measurable impact—not a good idea, since excessive caffeine consumption has risks, such as interfering with calcium absorption.
Metabolism booster #1
Trim the trans fat – You’ve heard they’re bad for you. But trans fats also slow down your body’s ability to burn fat. “They have an altered shape and make your biochemistry run funny,” Hyman says, explaining that trans fat binds to fat and liver cells and slows metabolism. Eating trans fat can also lead to insulin resistance and inflammation, both of which cripple metabolism and can cause weight gain.
Metabolism booster #2
Go organic – If you’re on the fence about whether to buy organic this news may sway you: Fruits, vegetables, and grains grown without pesticides keep your fat-burning system running at full-tilt because they don’t expose your thyroid to toxins, Hyman says. Nonorganic produce, on the other hand, “blocks your metabolism mainly by interfering with your thyroid, which is your body’s thermostat and determines how fast it runs, he explains.
Metabolism booster #3
Think protein – Your body digests protein more slowly than fat or carbs, so you feel full longer (this is especially true when you have it for breakfast). Plus, it may also giveyour metabolism a bump. In a process called thermogenesis, your body uses about 10 percent of its calorie intake for digestion. So, because it takes longer to burn protein than carbs or fat, your body expends more energy absorbing the nutrients in a high-protein diet. Another bonus: One recent study from Purdue University found that diets higher in protein may help preserve lean body mass, which is the best fat-burner of all.