Metabolism

 

Perhaps the greatest myth about metabolism is that it slows down with age and there is nothing you can do about it. Here's the truth: For the most part, you control your metabolism. How? Exercise! It's as simple as that. Including weight bearing activity into your exercise program is ideal not only to increase bone density, but also to help increase the body's metabolism. Muscle is very active tissue with high energy requirements. Even while we sleep, our skeletal muscles are responsible for more than 25 % of our total calorie use. An increase in muscle tissue causes a corresponding increase in our metabolic rate. Likewise, a decrease in muscle tissue causes a corresponding decrease in our metabolic rate. The gradual loss of muscle tissue in non-training adults leads to a 5 % reduction in metabolic rate every decade of life! This gradual decrease in metabolism is closely related to the gradual increase in body fat that typically accompanies the aging process. When less energy is required for daily metabolic function, calories that were previously burned by muscle tissue are stored as fat. Although our metabolism eventually slows down to some degree with age, this and other degenerative processes can be markedly delayed through regular strength training. When muscle mass decreases, the result is a decrease in muscular strength and endurance. For each decaded after the age of 25, 3 % to 5 % of muscle mass is lost. This is primarily attributed to changes in lifestyle and the decreased use of the neuromuscular system. However, several recent studies have reported significant strength gains in previously sedentary older adults following a program of regular exercise. The changes in body composition resulting from age are due to a decrease in muscle mass which in turn is due to a decrease in physical activity. Many people think that they have not changed their routine from when they were younger. Think about it.  Are you *really* still doing the same things that you did 10 or 20 years ago? I have heard people tell me that even though they are still active, their metabolism has slowed down and that is why they have gained 30 pounds. The truth was that they *thought* that they were still active. If you used to jog 10 miles every other day, but now you walk 5 miles once per week, that is a drastic change in activity level. For whatever reason, whether it is a health issue or just a change in schedule, it is still a change that makes a difference and it is the cause of a decline in metabolic rate. Regular physical activity preserves lean body mass, decreases fat stores and stimulates protein synthesis which reverses the adverse changes in body composition that is associated with growing older.

 

Recommended reading: Eat, Drink, and Be Healthy; The Harvard Medical School Guide to Healthy Eating by: Walter C. Willett, M.D.