Exercising is a better long-term solution to weight loss than dieting, because it has a more positive effect on your metabolism, which determines how fast your body burns calories. Exercising builds muscles, which burn calories more expeditiously than fat. Dieting, though, slows your metabolism, because "your body thinks you're starving," according to "Dr. Dean Ornish's Program for Reversing Heart Disease." When you cut your calorie intake, your body wants to protect you from losing too much weight too fast.
Energy
Dieting can be dangerous because you need a minimum amount of calories to survive, and more to work, exercise and perform other activities. Calories are a measurement of energy. How many you need depends on your size, gender and activity level, but "Essentials for Health and Wellness" estimates that women need 1,100 calories daily to keep their cells and internal organs working, while men need 1,300. Active men and women need 2,400 and 2,000 calories daily, respectively, according to The Merck Manual of Medical Information.
Comparison
You lose 1 pound when you burn 3,500 calories. An active woman eating 14,000 calories weekly needs to burn 17,500 calories weekly to lose 1 pound. "The Complete Guide to Walking" compared two women who were eating 2,000 calories daily. One tried to lose weight by eating 1,500 calories a day and not exercising. The other tried eating 1,750 calories daily and burning 250 calories daily via exercise. The woman who exercised lost significantly more weight because her metabolism increased, while the dieter's metabolism decreased.
Factors
Weight loss during an exercise session depends on your weight, the duration and intensity of the exercise, and the kind of exercise it is. You are exercising more intensely if your heart rate is faster. Your heart rate should be 65 to 70 percent of your maximum heart rate, which is 220 heartbeats per minute, minus your age, to "burn serious calories," according to "Walking" author Mark Fenton. Most people move faster when they are exercising more intensely, wrote Fenton.
Statistics
The Harvard Heart Letter analyzed the weight-loss effect of 158 activities. It found that running fast burned the most calories---1,466 calories per hour if you're 185 pounds and running 6-minute miles. If you're 125 pounds, you burn 990 calories an hour running a 6-minute mile, 750 calories an hour running 8-minute miles and 600 calories an hour running a 10-minute mile. Walking 4 miles an hour burns 400, 334 and 270 calories an hour if you weigh 185, 155 and 125 pounds, respectively.
Expert Advice
Every exercise session should include a warm-up and cooldown that consists of stretching your muscles, and a low-intensity aerobic exercise such as slow walking. Ornish recommends warming up for five to 10 minutes and cooling down for 10 to 15 minutes. Warming up instead of going suddenly from rest to intense exercise reduces your risk of injury. Cooling down instead of stopping suddenly reduces the chances that you will get a heart attack or stroke from blood pooling in your legs and not reaching your heart or brain, according to exercise expert Kenneth Cooper.
References
- Dr. Dean Ornish's Program For Reversing Heart Disease; Dr. Dean Ornish; 1996
- Essentials for Health and Wellness; Gordon Edlin, Eric Golanty, Kelli McCormack Brown; 2000
- The Merck Manual of Medical Information; 2003
- The Complete Guide To Walking; Mark Fenton; 2001
- Harvard Heart Letter: Calories Burned in 30 Minutes for People of Three Different Weights
- Start Strong, Finish Strong: Prescriptions for a Lifetime of Great Health; Kenneth H. Cooper, Tyler C. Cooper, William Proctor; 2007
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