A series of crash diets that are devoid of exercise strip the body of needed water, muscle, and fat. The fat returns in a flash when the dieting stops, yet only physical activity can rebuild the muscle. The body is left with a lower metabolic rate (the rate at which it burns calories) and a higher risk of future weight gain.
How do you get off the weight-gain roller coaster? After years of studying what works -- and what doesn't work -- in weight loss and control, the experts seem to have come to some agreement. They now favor lifelong, consistent changes in eating and exercise habits, instead of short-term diets and exercise binges.
Although you won't lose weight overnight, the result of the lifelong plan is a sustained increase in the body's percentage of lean body mass (muscle and bone) and a decrease in the body's percentage of fat.
The body usually maintains a delicate balance between the calories taken in as food and those burned up as "fuel." For instance, consuming 2,400 calories of food in a day and burning up 2,400 calories by sleeping, eating, walking, and performing other activities results in neither weight loss nor weight gain.
However, if there are any calories left over -- if, for example, you take in 2,400 calories and burn only 2,300 -- they are stored as fat. Storing 3,500 of these extra calories gives you 1 pound of fat. To lose weight, you must use more calories than you consume -- by eating fewer calories, by exercising, or, as the experts advise, by combining the two.
When you diet without exercising, your body reacts as if it were being starved, by lowering its metabolic rate. In other words, your body burns fewer calories in order to maintain the weight that its metabolic controls consider healthy and normal. The body may also use protein pulled from lean muscle tissue to provide extra calories.
What's more, inactivity can help lead to obesity. People who are obese, in turn, tend to become less active. This compounds their weight problem, completing a vicious cycle in which stress, anxiety, and tension lead to compulsive eating, which results in additional excess body fat; that extra fat further contributes to inactivity, which begets more weight gain -- causing even greater stress, anxiety, and tension.
As mentioned earlier, dieting without exercising also tends to rob the body of lean muscle tissue and water. (Weakness and dark, strong-smelling urine are signs of this muscle wasting.) But the body needs a certain amount of water to avoid dehydration. So when you replenish the water, some of the weight that was lost at the start of the diet is gained back.
However, the lean muscle tissue, which contributes to a fit and trim appearance, can only be regained through physical activity. Regular exercise, especially when combined with modest changes in diet, can help you break the vicious cycle of weight gain.
Walking is especially well-suited to play the exercise role. As a sustained, rhythmic workout, walking conserves and may build muscle while it burns calories. And muscle has a higher metabolic rate than fat. So the more muscle and the less fat you have, the more calories you burn while resting.
What about the old myth that exercise defeats the purpose of weight loss because it increases your appetite and makes you eat more? Even the experts don't agree on the exact relationship between appetite and exercise. Several studies suggest, however, that appetite may actually decrease when very sedentary people begin moderate exercise programs.
The important point to remember, however, is that walking burns calories without lowering your resting metabolic rate the way dieting alone does. By burning calories through exercise, you won't need to make such severe changes in your diet. That doesn't mean that you can eat anything you want. But you will be able to enjoy a balanced diet that includes regular meals and enough nutrients to build and maintain a healthy body -- and you won't have to starve yourself.
In addition, people who become more active tend to spontaneously shift their food choices in a healthier direction, opting for a better-balanced diet with less saturated fat and total calories and more fiber and fresh foods, according to Rose E. Frisch, Ph.D., associate professor of population sciences at the Harvard School of Public Health.
Wondering how many calories you can burn while walking? Read the next section for the answer.
To learn more about walking, see: