Why do we gain weight?
.jpg)
Why do many people tend to gain weight as they get older? The answer is both simple and complex. The simple answer is that they begin to take in more calories than they use or burn. Assuming the average adult burns 1800-2500 calories a day with minimal activity, an intake of the same amount of calories each day would allow the person to maintain a stable weight.One pound of fat equals about 3500 calories. Therefore, if a person eats 500 calories per day more than they use up, they will gain one pound per week (500 calories x 7 days = 3500 calories = one pound). As little as 100 calories per day excess intake will result in a ten pound weight gain in one year.
The more complex answer to why we gain weight, particularly with getting older, has to do with changes in the body's physiology. Several changes occur with aging. First, our metabolism slows after age thirty. Our bodies do not burn as many calories with the same amount of activity. Next, we lose lean muscle mass which also burns calories faster than the fat it may be replaced by. Perhaps most importantly, our activity level changes.
Physical activity is the most significant variable in the weight control equation. If 1200-1500 calories are used each day simply by breathing and having a heart beat (basal metabolic rate/BMR), only 500-1000 calories used each day are accounted for by activity of living. People with desk jobs (or flying jobs) and little physical activity may only use 600 calories each day above their basal metabolic rate. Those with moderate activity that requires some walking, such as a fuels handler at an FBO, may use 900 or more additional calories per day. Finally, people with physically demanding jobs, such as baggage handlers, may burn over a thousand calories more than their BMR daily. Obviously, the last group may eat more each day with less risk of gaining weight than the less active groups.
