A person loses 25% of his or her lean body mass and 75% of his or her fat when losing weight through calorie reduction alone. In combination with physical activity, the loss in body fat is 98%. Weight loss that is achieved with a combination of calorie restriction and physical activity is more effective. For maintenance of desirable body weight, a maintenance level of calories along with physical activity is recommended to preserve lean body mass and muscle tone.


The recommendations provided by the American College of Sports Medicine for weight loss and maintenance are as follows:

Pursue physical activity at least three times a week. Increasing it to four to five times a week is even more beneficial. Spread out the physical activity through the week rather than doing it on three or four consecutive days to decrease the risk of related injuries.

Physical activity should be done at 60 to 90% of the maximum heart rate.

To calculate the maximum heart rate, the following formula is used:

Subtract your age from 220 (beats per minute) to get the maximum heart rate. Then multiply this figure by the intensity level.

For example, a 50-year old woman exercising at 60% maximum would use the following calculation:

220 - 50 = 170 (maximum heart rate)

170 X 60% = 102 which is the target heart rate regardless of the type of physical activity he/she selects to do.

Physical activity at 60 to 70% of the maximum heart rate can be continued at a safe rate for a long period of time. If an exercise is too strenuous, conversation cannot be carried on during the physical activity (the person is out of breath).

According to the American College of Sports Medicine, physical activity of less than 2 times a week at less than 60% of the maximum heart rate, and for less than 10 minutes per day, does not assist in developing and maintaining fitness. If physical activity is discontinued, the fitness benefits are completely lost. Within 2 to 3 weeks the level of fitness is reduced, and within 3 to 8 months it is completely lost, and the person has to restart again.

Twenty minutes of continuous aerobic activity 3 days per week is recommended for weight loss. Examples of physical activity that are considered aerobic are: walking, running, jogging, hiking, swimming, bike riding, rowing, cross country skiing, and jumping rope.


Physical activity contributes to health by reducing the heart rate, decreasing the risk for cardiovascular disease, and reducing the amount of bone loss that is associated with age and osteoporosis. Physical activity also helps the body use calories more efficiently, thereby helping in weight loss and maintenance. It can increase basal metabolic rate, reduces appetite, and helps in the reduction of body fat.


Physical activity should be done at a rate that is appropriate for the person. An evaluation by an exercise physiologist is helpful to avoid injuries that can occur if physical activity is initiated without much consideration given to the type, duration of physical activity, and the physical condition of the person.