After growth has stopped at the end of adolescence, we produce less growth hormone which supported a higher metabolic rate as we grew in height and weight. As we age, we lose muscle mass which maintains a higher metabolism.
Weight lifting helps to maintain our muscle size and supports a higher metabolic rate because muscles do work which uses the food we eat as fuel. Muscles and organs perform the work which is reflected in our metabolic rate.
Exercising alone even if it reduces body fat thru aerobic exercise won’t necessarily increase our muscle mass unless weight lifting is also performed. I am not saying we need to become bodybuilder muscle size, just make the muscles you do have do more work so they grow in size.
Men continue to produce a consistent level of testosterone throughout life until about age 70 when testosterone levels usually drop. This drop in testosterone can lead to a loss of muscle mass unless men lift weights.
Women’s bodies increase the amount of body fat in response to estrogen. When women go thru menopause, their metabolic rate drops due to much lower production of estrogen. Unfortunately, body fat cells are not very metabolically active and just sit around waiting for a famine to provide fuel for our bodies.
Since our body (organs and muscles) burns many more calories than most people do during exercise, it is important to maintain our muscle mass in an effort to support a higher metabolic rate all day long. Exercise can increase our metabolic rate for up to 15 hours after exercise so it is good to exercise at least 30 minutes a day five days a week. Weight lifting every other day helps maintain our muscle mass and therefore an increased metabolism.
The good news is when your metabolism is higher, you can eat more food. Otherwise, when metabolism is low due to a smaller muscle mass, it doesn’t take as many calories to maintain your weight.