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.
According to a study in the Journal of Applied Physiology, strength training increases your resting metabolic rate, so you burn calories even when you're not working out. When it comes to strength training, doing compound exercises is one of the most effective ways to work several muscles at once and save time at the gym. Compound movements like a weighted squat to a shoulder press or a reverse lunge to a bicep curl will work multiple muscle groups, so you get more bang for your buck. 

Sprinkle a few hot peppers into your lunchtime soup or evening stir-fry. They temporarily boost your resting metabolic rate, according to research done at Laval University in Canada. Here's why: Capsaicin, a compound found in jalapeño and cayenne peppers, temporarily stimulates your body to release more stress hormones, such as adrenaline, speeding up your metabolism and thus increasing your ability to burn calories, says study coauthor Angelo Tremblay, director of the Institute of Nutraceuticals and Functional Foods at Laval. Bonus: The pepper-eaters had less of an appetite, Tremblay found, probably because the spiciness of the food made them feel full.

Weight loss doesn’t get easier than this: Simply drinking more water may increase the rate at which healthy people burn calories, according to a study in The Journal of Clinical Endocrinology and Metabolism. After drinking approximately 17 ounces of water (about 2 tall glasses), participants’ metabolic rates increased by 30 percent. The researchers estimate that increasing water intake by 1.5 liters a day (about 6 cups) would burn an extra 17,400 calories over the course of the year—a weight loss of approximately five pounds!
It's essential for carrying the oxygen your muscles need to burn fat, says Tammy Lakatos, RD, co-author of Fire Up Your Metabolism. Until menopause, women lose iron each month through menstruation. Unless you restock your stores, you run the risk of low energy and a sagging metabolism. Shellfish, lean meats, beans, fortified cereals, and spinach are excellent sources. Check out this list of foods with more iron than beef.

Aim for a breakfast that has plenty of high-fiber carbs: When researchers at the University of Sydney in Australia compared the effects of high-fat and high-fiber-carbohydrate breakfasts, they discovered that people who ate the fatty meal got hungry sooner afterward. "High-fiber carbohydrates take longer for your body to digest and absorb than fats; thus they don't cause rapid changes in your blood sugar, so your hunger is kept at bay longer," says study coauthor Susanna Holt, Ph.D. Some good choices: a bran-rich breakfast cereal with low-fat milk; whole-grain toast topped with low-fat ricotta and sliced banana or berries; an egg-white veggie omelette with whole-grain toast.
Strength training is another great way to make sure your metabolism is at its peak. Through strength training, you can tone your muscles and boost your metabolism. The great thing about muscles, other than looking lean, is that they burn more calories than fat. No need to bust out the big weights for strength training — try some basics, like push-ups, sit-ups, resistance bands, or yoga.
Skimping on sleep can derail your metabolism. In a study at the University of Chicago, people who got four hours of sleep or less a night had more difficulty processing carbohydrates. "When you're exhausted, your body lacks the energy to do its normal day-to-day functions, which include burning calories, so your metabolism is automatically lowered," explains Peeke.
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