The key to weight control is keeping energy intake (food) and energy output (physical activity) in balance. To lose weight, you must burn more calories than you eat.

Exercise is the best way to do this. When you exercise regularly, you build stronger muscles, even if you do not work out with weights. Muscles use more calories than fat throughout the day, even while you are resting. This helps boost your metabolism.

How much exercise you need to make a difference in your weight depends on how much you eat and what activity you are doing. A medium-sized adult would have to walk more than 30 miles to burn up 3,500 calories, the equivalent of one pound of fat. Although that may seem like a lot, you don't have to walk the 30 miles all at once. Walking a mile a day for 30 days will achieve the same result, as long as you don't eat more than usual.

If you eat 100 calories a day more than your body needs, you will gain approximately 10 pounds in a year. You could lose the weight or keep it off by doing 30 minutes of moderate exercise daily. The combination of exercise and diet is the best way to control your weight.

If you are doing a regular program of strength training (weight lifting), your muscles will get bigger. It is possible that your overall weight will increase, because muscle weighs more than fat. However, your clothes will probably fit better and your body will be more toned. Your body composition is a better indicator of your overall health than the number on the scale.

See also: Body mass index

Making a Commitment

The decision to keep fit requires a lifelong commitment of time and effort. Exercising and eating right must become things that you do without question, like bathing and brushing your teeth. Unless you are convinced of the benefits, you will not succeed.

Patience is essential. Don't try to do too much too soon and don't quit before you have a chance to experience the rewards. You can't regain in a few days or weeks what you have lost in years of sedentary living, but you can get it back if you keep at it. And the prize is worth the price.

Health Benefits of Exercise

Regular exercise -- including walking -- decreases your risk of:

• Anxiety
• Death
• Depression
• Heart attack
• High blood pressure
• Obesity
• Osteoporosis
• Some cancers
• Stroke

Exercise also improves good cholesterol (HDL) levels.

You should always check with your health care provider before you begin any new form of exercise.

American Diabetes Association. Position statement: physical activity/exercise and diabetes. Diabetes Care. 2004;27(1):S58-S62.

American Diabetes Association. Position statement: weight management. Diabetes Care. 2004;27:2067-2073.