Ever wonder why your best friend can go through a pint of Ben & Jerry's without gaining a pound while just one spoonful goes straight to your hips? The answer lies in your metabolism, that little engine in your body that burns calories all day, every day. Because of genetics, some women burn fat faster than others. But age, weight, diet, and exercise habits also play a role. "As women age, their metabolisms slow down, mainly because they are losing five or six pounds of muscle each decade starting in the mid-20s," explains fitness expert Wayne Westcott, Ph.D., fitness research director of the South Shore YMCA in Quincy, Massachusetts. Translation: You may be burning 100 fewer calories a day at 35 than at 25. But there are easy things you can do to stoke your fat-burning potential. "There's no reason you can't have the same metabolism in your 30s and 40s that you had in your 20s," stresses Pamela Peeke, M.D., author of Fight Fat After Forty. These are the simple tips our experts shared on how to crank up your internal flame.
Don't overdo calorie cutting.
Putting yourself on a very-low-calorie diet is a surefire way not to lose. "Your body is programmed to defend your usual weight," says Liz Applegate, Ph.D., professor of nutrition at the University of California at Davis and author of Bounce Your Body Beautiful. "So if you suddenly drop 1,000 calories from your diet, your resting metabolic rate [the number of calories your body burns to maintain basic bodily functions, such as breathing and heartbeat] will automatically slow down, because your body now assumes that you're starving."
So how many calories should you consume? Depending on your level of activity, you can safely lose anywhere from half a pound to two pounds a week if you multiply your current weight by 11, says Applegate. (For example, if you're 120 pounds, aim for around 1,320 calories a day.) Unless you're less than five feet tall, don't let your daily calories dip below 1,200. "Research shows that women who consume less than this amount see their resting metabolic rate plummet by as much as 45 percent," notes Dale Huff, R.D., a St. Louis nutritionist.
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Believe it or not, it may be the most important meal of the day as far as metabolism (and weight loss) is concerned. Breakfast eaters lose more weight than breakfast skippers do, according to studies. "Your metabolism slows while you sleep, and it doesn't rev back up until you eat again," explains Barbara Rolls, Ph.D., professor of nutrition at Penn State University and an author of The Volumetrics Weight-Control Plan. So if you bypass breakfast, your body won't burn as many calories until lunchtime as it could. That's why it's smart to start the day with a solid 300- to 400-calorie meal; it jump-starts your metabolism.
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.
Pile on the protein.
Research shows that getting plenty of protein can boost your metabolism, causing you to burn an extra 150 to 200 calories a day, says Jeff Hampl, Ph.D., R.D., a spokesman for the American Dietetic Association. "Protein is made up mainly of amino acids, which are harder for your body to break down [than fat and carbs], so you burn more calories getting rid of them," he explains.
That doesn't mean you have to live on the high-protein Atkins diet. But you should make sure that 10 to 35 percent of your total daily calories comes from protein. So if you're on an 1,800-calorie diet, 360 to 630 of those calories should come from lean sources of protein, such as fish, chicken, low-fat cheese, yogurt and legumes. "Aim to have a serving of protein, such as nuts, a small can of tuna, or a piece of low-fat string cheese, at every meal and snack," says Hampl.
Nibble all day.
It sounds counterintuitive; why would you eat continually if you wanted to lose weight? But eating five to six mini meals rather than three larger meals every day keeps your metabolism humming 24/7. "It will also prevent you from going without food so long that you become so hungry you overeat," says Peeke. Try not to let more than four hours elapse between meals and make sure each meal includes protein, for an extra metabolic boost. If you eat a high-fiber breakfast of cereal and fruit first thing, for example, have a midmorning snack, such as yogurt and fruit; lunch (try four ounces of chicken or fish on top of a leafy green salad); another snack, like a banana and a piece of low-fat cheese, in the late afternoon; and a light dinner (think four to six ounces of turkey, salmon, or another lean source of protein with steamed veggies).
Go for "good" carbs.
Refined carbs, such as bagels, white bread, and potatoes, create a surge in insulin that in turn promotes storage of fat and may drive down your metabolic rate, says Louis Aronne, M.D., an obesity specialist at New York Presbyterian Weill Cornell Medical Center, who recommends high-fiber carbs instead. "It's important to keep carbohydrates in your overall diet, but focus on vegetables, fruits, and whole grains, which have less of an impact on insulin levels," he explains.
Thinking about having a cocktail-or two-before dinner? Think again. Having a drink before a meal causes people to eat around 200 calories more, several studies show. Drinking with dinner isn't such a good idea either: Other research has found that the body burns off alcohol first, meaning that the calories in the rest of the meal are more likely to be stored as fat. If you do have a cocktail craving, stick to wine, which packs only 80 calories a glass-or minimize the calories by drinking a white-wine spritzer (two ounces of wine mixed with two ounces of seltzer).
Load up on low-fat dairy: Women who consumed milk, yogurt, and cheese three to four times a day lost 70 percent more body fat than women who didn't eat dairy in a study published in the January 2003 American Society for Nutritional Sciences Journal of Nutrition. The reason: Calcium, along with other substances in dairy, actually revs up your metabolism, telling your body to burn excess fat faster, according to study author Michael Zemel, Ph.D., director of the Nutrition Institute at the University of Tennessee in Knoxville. And no, fortified o.j. won't do the trick. The best results come from dairy products instead of from other calcium-rich foods (like broccoli), calcium-fortified products (such as orange juice) or supplements. Women reap the largest fat-burning benefit when they consume three servings of dairy and 1,200 milligrams of calcium a day, Zemel's research shows.
Spice up your soup.
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.
Experts say weight training is the best way to crank up your resting metabolic rate. "As you get older, your resting metabolic rate drops, but weight training can rev it right back up again: A pound of muscle burns up to nine times the calories a pound of fat does," explains fitness expert Westcott. In fact, a woman who weighs 130 pounds and is muscular burns more calories than a sedentary 120-pound woman of the same height. Regular strength training can increase your resting metabolic rate anywhere from 6.8 to 7.8 percent. (That means that if you weigh 120 pounds, you could burn around 100 more calories a day, even when you're just watching TV.)
Don't think you have time to hit the gym circuit? You can get great results with only two 15-minute lifting sessions a week. Westcott's research, published in the journal Medicine & Science in Sports & Exercise in January 1999, found that doing just one set of 10 reps reaps about the same muscle-building benefits as three sets, as long as they're performed to muscle fatigue. Bonus: Weight training also gives your metabolism a short-term boost. When women lift weights, their metabolisms remain in overdrive for up to two hours after the last bench press, allowing them to burn as many as 100 extra calories, according to a study published in June 2001 in Medicine & Science in Sports & Exercise.
Rev up your workouts.
Adding interval training-bursts of high-intensity moves-to your workout is a great metabolism booster. "Studies have shown that people who do interval training twice a week [in addition to cardio] lose twice as much weight as those who do just a regular cardio workout," says obesity specialist Aronne. You can easily incorporate interval training into your workout by inserting a 30-second sprint into your jog every five minutes or by adding a one-minute incline walk to your treadmill workout. "Since your body is working harder, it's a more intense workout -- and you therefore burn more calories," says Westcott. On other days, shake up your routine with 40 minutes of cross-training. Ideally, aim for two 20-to-40-minute interval-training sessions and two 20-to-40-minute cross-training sessions a week.
Break up your exercise routine.
Whenever possible, slice each of your workouts into two smaller sessions. For example, do a 15-minute weight-lifting session in the morning, then do your 30-minute walk on your lunch hour or at night. You'll burn an extra 100 to 200 calories that day, explains Kelly Tracy, M.A., fitness coordinator at Duke University Diet and Fitness Center. Don't have time? Just add in some stair climbing or short walks throughout the day. Even small bursts of activity are enough to get your metabolism revved, according to a study in the scientific journal Nature. "I call it the mini stoke: For five minutes out of every hour, get up and do something, even if it's just walking around your office," says professor of medicine Peeke. "You can end up burning a couple of hundred extra calories.
Sweat out your PMS.
It's tempting to curl up on the couch the minute PMS mood swings and bloat strike, but you'll lose more weight if you exercise during those two weeks before your period, according to a recent study at the University of Adelaide in Australia. "Women burned about 30 percent more fat for the two weeks following ovulation to about two days before menstruating," says study coauthor Leanne Redman. Here's why: The reproductive hormones estrogen and progesterone are at their peak then-and because they promote the body's use of fat as energy, more fat is burned off when you exercise during this time.
Get some shut-eye.
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.
There are easy ways to get a good night's sleep, according to the National Sleep Foundation. Schedule your workouts earlier in the day; exercising within two to three hours of bedtime can keep sleep at bay. And try soaking in a hot bath, since studies show that warm water makes it easier to fall asleep.
Long-term stress can make you fat, studies have found. "When you're chronically stressed, your body is flooded with stress hormones, which stimulate fat cells deep in the abdomen to increase in size and encourage fat storage," says Peeke. "I call this toxic weight, because fat deep within your belly is more likely to increase your risk for heart disease, diabetes, and cancer." And stress hormones spark your appetite, making you likely to overeat.
So what's a frazzled woman to do? Make a list of all the things that relax you: playing with the dog, writing in your journal, even listening to classical music. Then allow yourself 10 to 15 minutes every day to kick back and enjoy one of these activities.
You may have heard about these so-called metabolism boosters-but do they really work? Should you try them? Here's the skinny:
1. Breaking a sweat first thing in the morning. Heard that the early-bird exerciser burns the most calories? Don't buy it, says nutritionist Dale Huff. What time of day you exercise makes no difference to your metabolism. Schedule your sweat sessions for when they're convenient for you, whether it's in the morning, in the afternoon, or during your lunch hour; you'll lose weight at any time of day.
2. Vitamin B12. This vitamin is flying off health-food-store shelves, with women swearing that megadoses help boost their metabolism; but experts say no research bolsters anecdotal claims. "The B vitamins are essential, but they won't speed up your metabolism," says professor of nutrition Jeff Hampl.
3. Bikram yoga. Women all over the country are saying om to this new form of yoga, in which you perform standard poses in sweltering heat (some rooms are heated to 100 degrees). But while this may temporarily up your metabolism, doctors say you should not sweat it out this way. "Being in hot rooms when you're already generating heat is dangerous," says Pamela Peeke, M.D. "You're at risk for dehydration, electrolyte imbalance, and excessive strain on your heart."
4. Not eating after 6 p.m. Research has shown no link between evening eating and weight gain. You may be more likely to overeat when you nosh nocturnally as opposed to during the day, says Hampl, but your metabolism does not slow down significantly after 7 p.m. (though it does once you fall asleep).
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