Brew up some green tea: "It's the closest thing to a metabolism potion," says Tammy Lakatos Shames, R.D., author of Fire Up Your Metabolism: 9 Proven Principles for Burning Fat and Losing Weight Forever. The brew contains a plant compound called ECGC, which promotes fat burning. In one study, people who consumed the equivalent of three to five cups a day for 12 weeks decreased their body weight by 4.6 percent. According to other studies, consuming two to four cups of green tea per day may torch an extra 50 calories. That translates into about five pounds per year. Not bad for a few bags of leaves, eh? For maximum effect, let your tea steep for three minutes and drink it while it's still hot.
More: The Everything Guide to Tea
Undo damage with dairy: Hey, it happens. There are days when no salad on earth can possibly overcome the seductive power of French fries. But you can make up for it with a calcium-rich afternoon snack, like eight ounces of milk or six ounces of low-fat yogurt. Calcium helps your body metabolize fat more efficiently by increasing the rate at which it gets rid of fat as waste (yes, that kind), reports a study from the University of Copenhagen. Sorry, supplements don't have the same effect.
More: How Milk Does a Body Good
3. When You Go Food Shopping
Choose organic produce: You wouldn't fill your car engine with pesticides, right? Hell, no. Researchers in Canada found that dieters with the most organochlorides (chemicals found in pesticides) stored in their fat cells were the most susceptible to disruptions in mitochondrial activity and thyroid function. Translation: Their metabolism stalled. Can't afford a full organic swap? Go to foodnews.org/fulllist for the most (and the least) contaminated foods, then adjust your shopping list accordingly.
More: Eat Organic for Better Health and Faster Metabolism
Seek heat: It turns out capsaicin, the compound that gives chili peppers their mouth-searing quality, can also fire up your metabolism. Eating about one tablespoon of chopped red or green chilies boosts your body's production of heat and the activity of your sympathetic nervous system (responsible for our fight-or-flight response), according to a study published in the Journal of Nutritional Science and Vitaminology. The result: a temporary metabolism spike of about 23 percent. Stock up on chilies to add to salsas, and keep a jar of red pepper flakes on hand for topping pizzas, pastas, and stir-fries.
Grab some metal: Women lose iron during their period every month. That can throw a wrench into your metabolic machine, because iron helps carry oxygen to your muscles. If your levels run low, muscles don't get enough O2, your energy tanks, and your metabolism sputters, Shames says. Stock up on iron — fortified cereals, beans, and dark leafy greens like spinach, bok choy, and broccoli.
More: Top 3 Nutrients for Female Athletes
4. When You Work Out
Mix things up with intervals: You're always looking for a way to shorten your workout, right? Well, step up your intensity and you'll burn the same number of calories or more in less time. In one Australian study, female volunteers either rode a stationary bike for 40 minutes at a steady pace or for 20 minutes of intervals, alternating eight seconds of sprints and 12 seconds of easy pedaling. After 15 weeks, those who incorporated the sprints into their cardio workouts had lost three times as much body fat — including thigh and core flab — compared with those who exercised at a steady pace. Bursts of speed may stimulate a fat-burning response within the muscles, says lead researcher Ethlyn Gail Trapp, Ph.D. Whether you ride, run, or row, try ramping things up to rev your burn: Start by doing three eight-second all-out, can't-talk sprints with 12 seconds at an easy pace between each effort. Work your way up until you can do 10 sprints over 20 minutes.
More: Infographic: Your Complete Interval Training Guide
Take it slow: This isn't easy, but when you strength train, count to three as you lower the weight back to the start position. Slowing things down increases the breakdown of muscle tissue&mash:yeah, it sounds bad, but all that damage you're incurring is actually a good thing. The repair process pumps up your metabolism for as long as 72 hours after your session, according to researchers at Wayne State University. But pass on those featherweight dumbbells—you need to use weights that are heavy enough that you struggle to complete the final few reps.