Growing older is always accompanied by gradual loss of muscle that is replaced by fat. Despite gaining weight from about 25 onward, we also lose muscle, so that at age 50 our total muscle mass is about 70 percent of that at age 30, and by aged 80 half of our peak muscle mass is lost. Total body weight remains constant as loss of muscle is replaced by even more fat. Thus even if your weight has remained totally constant for decades, you will have proportionally more fat at age 60 than you did at 25.

Although muscle loss is in part because of inactivity, a major reason is an alteration in a primitive muscle cell called a myocyte. When muscle fibers are lost or damaged, myocytes proliferate, differentiate and replace them. With age, myocytes loose their ability to repair damaged muscle leading to loss of muscle mass.

Muscle loss leads to weakness that has profound implications. Weak muscles lead to weak bones and osteoporosis. Weak muscles together with alterations in tendons and ligaments contribute to joint instability that leads to osteoarthritis. Muscle weakness, osteoporosis and osteoarthritis contribute to difficulties with gait and balance, an inability to walk without assistance and eventually to a dreaded fall. And remember: More people die of falls and fractures than from prostate, breast and colon cancer combined.

There are other negative consequences of reductions in muscle mass. Muscle is the most metabolically active component of the body. Decreased muscle means profound reductions in energy or calorie needs. So older persons consume less food, less protein and less vitamins and minerals each day. And yet the requirements for protein and most vitamin and minerals actually increase with age. Less food intake, less protein and nutrient intake leads to a much higher risk of severe malnutrition, particularly if nutritional needs are increased by the presence of a serious illness.

Another untoward effect of less muscle and more fat is the development of insulin resistance, which impairs the ability of the hormone to deliver glucose to the cell and leads to diabetes.

While we cannot stop the muscle mass loss that accompanies aging or, as yet, return the bones of an 80-year-old women into those of a teenage athlete, we can make bones stronger and reduce all of the negative effects of age-related muscle loss merely by exercising. Perhaps one of the greatest breakthroughs in the prevention of frailty comes from the research of Dr. William Evans, who showed that even in 90-year-olds, resistance training or exercising with weights can increase strength by over 170 percent, increase muscle and bone mass, improve metabolism, increase food intake and even improve mood. More importantly gait and balance are dramatically improved, leading to an 80 percent reduction in fall and fracture risk. Something as low tech as exercising with weights can prevent dependency and, most importantly, save billions in health care costs while simultaneously improving quality of life.

Weight training has become an integral part of the rehabilitation of older persons who are unable to get around. It is also one of the key ways to prevent frailty and dependency in old age. To be effective, the weight used must be sufficient in that the muscle being exercised is virtually exhausted after 8 to 10 repetitions. I do not recommend buying weights and exercising at home. In general, most don’t exercise adequately, are more prone to injury and do not sustain the effort. Weight training must be done under the supervision of a trainer or a physical therapist, at least until you have learned the ropes. No matter the disability, be it a previous stroke, joint disease or other medical problem, there is a program that can be designed to meet your needs. 

I strongly recommend that no matter your age, you join a health club and begin both an aerobic and resistance-training program. Not only will the quality of your life be improved but your risk of many illnesses will be reduced, and believe it or not, your life will be prolonged.

Dr. David Lipschitz is the author of the book “Breaking the Rules of Aging.” To find out more about Dr. David Lipschitz visit