Frustrating as it may seem, banishing extra fat isn't impossible. Study after study has shown that the clincher, after cutting back on calories, is exercise. But as you charge into the gym, don't forget to enlist one of your best fat-fighting allies: your own muscles.
If you want to get into shape, aerobic workouts can't be beat for their power to tune up the heart and lungs. Aerobics will also tone the muscles you're using. But pumping iron can be another potent weapon in the battle against the bulge. Weight training will not only shore up your bones, build additional muscle mass, and make it easier to heft grocery bags or firewood, it can also help hold the line on your waistline.
Lose what you don't need
If you're dieting, weight lifting can help you lose fat instead of muscle and bone. Most people don't realize it, but when they diet, only about 60 to 75 percent of the weight they lose is actually fat. So if you shed 20 pounds, five or six of those pounds are from nonfat tissue, including muscle, bone, and water -- leaving your body weaker. But exercise, particularly the iron-pumping kind, can preserve muscle and bone, so that up to 85 percent of what you trim is fat, says Dale Schoeller, a nutrition researcher at the University of Wisconsin at Madison.
We all tend to fatten up as we get older, and one key culprit is the dwindling of muscle mass that begins in our 20s or 30s. After 40, we lose roughly a third of a pound of brawn a year. And since muscle burns more calories than fat does, our metabolism slows down. In women, who start out with proportionally less muscle than men, this process takes a bigger toll on the waistline. The average female gains around 20 to 25 pounds of fat between the ages of 20 and 50.
Weight training can also raise a person's metabolic rate for as long as 12 hours after exercising. That means that if you lift weights, your body will burn calories faster. But whether regular exercise generally increases your metabolism over the long-term remains controversial, says Glenn Gaesser, an exercise physiologist at the University of Virginia in Charlottesville.
One study in the Netherlands found that 18 weeks of weight training by young men sped up their metabolism by 9 percent. Other studies haven't found such a benefit. Nonetheless, Gaesser and others believe that by maintaining muscle, weight lifting can help minimize the metabolic downturn that occurs as you get older.
Here's the math: A pound of muscle burns five to 10 calories daily, even if you're lying on the couch. With a moderately strenuous weight-lifting regimen, women can gain one to two pounds of muscle after three months; men rack up about twice as much. Two extra pounds of brawn would thus consume 10 to 20 calories daily. That seems like small change, but over months and years, it can really add up. "Ten calories a day is 3,650 calories a year, which is equivalent to about a pound of body fat," says Gaesser. Over 20 years, that extra bit of muscle could keep you from putting on 20 pounds. "So it can make a rather sizable difference in the long term."
Indeed, nutrition researcher Miriam Nelson, director of the Center for Physical Fitness at Tufts University, often sees weight lifting open the door to a trimmer body. In one study, she put 10 overweight women on the same diet, but half of them lifted heavy weights twice a week. Both groups ended up around 13 pounds lighter on the scale. But that wasn't the whole story. On average, the diet-only crew lost only 9.2 pounds of fat, whereas the lifters actually lost 14.6 pounds of fat and gained 1.4 pounds of muscle.
Which points up a neat thing about strength training: You may not necessarily lose more weight, but you can still gradually slim down as you trade fat for brawn. Contrary to female fears, crunching dumbbells won't turn women into the Incredible Hulk. If anything, it'll make them smaller as they replace jiggly fat with compact muscle, says Nelson. Even more gratifying, people who pump iron notice striking improvements in strength fairly quickly, giving them more stamina for walking or biking. Two more major long-term bonuses, especially for older women: You get stronger bones and better balance.
Based on her research, Nelson lays out a program of diet plus aerobic and strength exercise in her book, Strong Women Stay Slim, and on her Web site, StrongWomen.com. The regimen has won glowing praise from readers. One 49-year-old battled weight all her life until she tried Nelson's plan a few years ago. "I wear clothes two sizes smaller than I used to wear at this [same] weight," she wrote in a message posted at StrongWomen.com. "... I have run and done aerobics for years, and nothing compares to weight lifting!"
While that's inspiring, other experts caution that not everyone will get such fabulous results. "For some, it's going to be a lot harder," warns Gaesser. For those people, it's helpful to remember that any kind of exercise will earn you a big payoff -- in better health. Working out can do more than improve strength and endurance; it also helps to lower blood pressure and cholesterol and stave off diabetes. Even strength training can help protect the heart, though to a lesser degree than aerobic exercise. And perhaps most important, staying active will do wonders for your self-confidence. As Gaesser puts it, exercise simply makes you feel good.
To get started, Nelson recommends doing five essential weight-lifting exercises three times a week, and walking or biking at least three times a week. Can't fit all that exercise into your life? Check out Gaesser's book, The Spark. Breaking up your workout time into 10-minute sessions, he explains, is just as good as doing it all at once.
American College of Sports Medicine. "Strength Training for Bone, Muscle, and Hormones." Current Comment, http://www.acsm.org/comments.htm
American College of Sports Medicine. "Resistance Training in the Older Adults." http://www.acsm.org/comments.htm
Gaesser, Glenn A. The Spark. Simon and Schuster, 2001
Nelson, Miriam E. and Sarah Wernick. Strong Women Stay Slim. Bantam Books.
Votruba, S.G. et al. "The Role of Exercise in the Treatment of Obesity." Nutrition, Vol. 16.
Van Etten, L.M.L.A et al. "Effect of an 18-week weight-training program on energy expenditure and physical activity."
Interviews with Glenn Gaesser, Gaesser, an exercise physiologist at the University of Virginia in Charlottesville; and Dale Schoeller, nutrition researcher at the University of Wisconsin at Madison.