This example illustrates the importance of exercise as part of a weight loss and weight maintenance program. Our client is 5 feet 8� inches tall, works behind a desk in an office, and does not exercise. Our client's weight has been steady at 200 lbs for the last 6 months. To maintain this weight, our client consumes 3,000 calories of food and drink per day.
Using bioelectrical impedance, we have measured that our client has 30% body fat. Our client is classified as medically obese (class I) based on the client's height and weight.
Our client has set an objective of reaching a target weight of 166 pounds. This will put our client at the upper end of the normal weight range based on the body mass indicator.
We have designed a customized weight loss diet that will result in our client losing 2 pounds per week. This will require our client to eat 1,000 calories per day less than is being used.
Let us consider 2 cases. The first case relies on diet alone to achieve weight loss. In this case, our client will need to initially reduce the amount of calories consumed from food and drink to 2,000 per day to achieve a rate of weight loss of 2 pounds per week. However, the weight that the client will lose will be both body fat and lean muscle mass (which we assume to be in proportion to the starting body composition). The loss of lean muscle mass will cause the metabolic rate of our client to fall as weight is lost. This means that in order to lose 2 pounds per week over the 17 week target period, our client must reduce the calories taken in per day from 2,000 at the start to only 1,585 at the end. So our client must reduce the calories eaten by over 20% just to maintain the target rate of weight loss!
In the second case, our client adopts a moderate exercise program that includes strength training so that the amount of fat free (or lean muscle) mass remains the same throughout the 17 week period of weight loss. The exercise program itself burns off 250 calories per day, but even more importantly our client no longer needs to reduce the amount of calories eaten each day as the program progresses. In this case, our client needs to eat and drink 2,250 calories per day for the entire 17 week period of weight loss. At the end of the weight loss period, our client is eating 665 calories per day more than in the case where there was no exercise component. 250 calories per day came directly from the exercise while 415 calories per day came from maintaining the client's fat free mass. Because all of the client's weight loss came from the loss of fat, the client's body fat percentage has fallen from 30% to 16%.
In both cases, our client has lost 34 pounds in 17 weeks. In the first case, our client had to sharply cut back on the amount of food and drink consumed per day and in the end still had a relatively high body fat percentage, although the weight was within the target range. In the second case, our client had to moderately reduce the amount of food and drink consumed per day, lost unwanted body fat, and achieved the weight goal. Take your choice!
