Sarcopenia (muscle wasting) and Aging

(Adapted from the Nutrition Action Letter)

Both men and women begin to lose significant muscle mass in their 40's and 50's - partially due to aging and partially due to a sedentary lifestyle. Unfortunately, most people are unaware of what is going on, because the early muscle loss doesn't hold them back. It is only after they reach a point where they can no longer go grocery shopping or live independently, that people realize that there is a problem.

Why do we lose muscle? There is a slowdown in muscle metabolism as we get older. Our ability to synthesize muscle protein decreases. Also, there is too little muscle-stimulating physical activity. For 80 to 90 percent of adults, if they don't do the right kind of physical activity regularly, they are going to end up with sarcopenia by the time they are in their 60's and 70's. It's also of interest that while both men and women lose muscle as they age, women start out with less muscle and wind up much weaker. Since women live longer, they will be dealing with the effects of sarcopenia much more than men. Hormones (testosterone in men, and estrogen in women) drop with age and these are important for muscle growth in each gender, and we lose IGF (insulin-like growth factor) which is also critical for muscle growth.

Food: We eat less as we get older and in particular we eat less protein, the nutrient that builds muscle tissue. Studies have shown that in order to maintain muscle mass, people from their 50's onward who were exercising (muscles) needed at least 25 per cent more protein than the RDA (recommended dietary intake) level. To gain muscle tissue, they needed to consume 50 percent more protein than the RDA level. This means you should target about half your weight in pounds to get the proper grams (65 grams of protein a day for someone who weighs 125 pounds). Remember, eating protein alone won't build muscle; you need to exercise the muscles and then get adequate protein.

Why sustain muscle mass? Muscle (protein) burns most of the calories our body uses and muscle burns calories at a higher rate than fat tissue does. So the less muscle you have, the fewer calories you burn. An increase in body fat to muscle mass puts you at greater risk for chronic conditions like cancer and heart disease. Also, we have weaker bones when we aren't using muscles. Lastly, balance is severely affected as we lose muscle.

There is a condition called ‘sarcopenic obesity'. In this condition, you have a thin person (who is happy with ‘their weight') yet most of their weight is made up of fat and not muscle (more commonly seen as we get older). This is a very dangerous condition, as the person is at high risk for falls, infections, spontaneous fractures of bones and limited ability to be active.

In order to keep your muscles, you must do exercise. A combination of weight bearing and resistance training is the best. Strength training can increase muscle strength by 40 percent just in two months of training.

So, think for your future. You want to be independent and healthy and to do so, you need to exercise regularly. Strength training is not just for the younger person trying to ‘look good'. It's up to all of us to maintain healthy bones, balance, immunity and independence.