Exercise does help you control your weight, but maybe not in the way you think. When you do the math, exercise won't help you lose much weight when you're overweight — as it turns out, studies have shown that cutting calories works much better than trying to burn off any extra calories through increased physical activity.
Where exercise really shines is in helping you to keep off the weight once you've lost it. Exercise also is pretty critical for healthy aging generally.
Exercise: Weight Control and Maintenance
Here's the problem with exercise purely as a weight loss tool: it just doesn't burn that many calories. For example, jogging moderately for 40 minutes burns around 400 calories — around the same amount of calories as in a crumb cake donut or a medium-sized sugar-sweetened coffee drink.
Since you need to burn about 3,500 calories in order to lose one pound; if you jog for 40 minutes eight or nine times you will have jogged off one pound (assuming you've stayed away from the donuts and coffee in the meantime). If you prefer to walk briskly rather than jog, you should expect to burn about 300 calories for that same 40 minutes on the treadmill, making it even more difficult to walk off the extra weight.
The truth is that cutting calories — skipping those donuts and coffee and cutting back generally on your food intake — will allow you to reach your weight loss goals much more quickly than exercise.
So Why Exercise At All?
Medical studies do show that once you've lost some weight, becoming more physically active will help prevent you from regaining it. This may be because a regular exercise program increases your metabolism, which means you burn more calories throughout the day — even when you're sleeping.
Other benefits of exercise for weight control and healthy aging include:
- Maintaining your muscle mass: As we get older, we tend to lose muscle and gain fat. In fact, between age 30 and age 80, about 15% of your lean muscle will disappear, resulting in a lower metabolism (and possibly weight gain). But you can use exercise to help maintain your muscles and keep your metabolism higher.
- Muscle building and repair: After exercising your body must repair tired muscles and build up new ones. Since all of this takes calories to do, exercising more will help you control your weight.
- Making digestion inefficient: It is possible that exercising after eating will make digestion less efficient, thereby allowing calories that would have been absorbed into your body to pass through.
- Helping you make good choices: Exercise reduces stress, helps you sleep, and makes you feel good. All of these reduce your tendency to eat poorly.
Exercise also can help cut your risks for such conditions as heart disease and diabetes and may help you manage your risk if you've already been diagnosed with a chronic illness. It also can give you more energy generally and has been shown to improve older adults' quality of life.
There's no right exercise for everyone. Generally, the National Institutes of Health recommends that adults get about 150 minutes of moderate physical activity per week. That can translate into 30 minutes of brisk walking five times per week.
Although exercise is safe for almost everyone, you should talk with your doctor about your exercise plans. She may be able to help you craft a weight control program that includes exercise and healthy eating and that will help you meet your goals.