Why We Gain Weight as We Age (The Real Reason)

Many of us have experienced it firsthand: As the years go by, the pounds become more difficult to keep off. But have you ever wondered exactly why we experience weight gain as we age? Hint: Your eating habits actually aren't to blame.

There are a variety of reasons, explains Dr. Caroline Apovian, the Director of the Nutrition and Weight Management Center at the Boston Medical Center, professor at the Boston University School of Medicine, and the vice-president of The Obesity Society. A change in hormones, a more sedentary lifestyle, and an increase in stress and decrease in sleep due to added responsibilities are just a few.

"But a major reason for middle aged weight gain is the natural muscle loss we all experience," Dr. Apovian, the author of The Age-Defying Diet and The Overnight Diet: The Proven Plan for Fast, Permanent Weight Loss, says. "The amount of lean muscle mass we have is the primary determinant of metabolic rate. In other words, the more muscle mass we have, the more calories we will burn. Our muscle mass naturally begins to decline around age 30, and that process, called sarcopenia, accelerates around age 40. Unless something is done to actively protect and build up that lean muscle mass, our bodies will require fewer calories, our metabolisms will slow, and the lost muscle will be replaced by fat."

So, what can you do to prevent sarcopenia? Dr. Apovian offers three tips:

1. "Exercise with weights at least twice per week, building up in both weight and intensity as you progress," she says.
2. "Eat a diet rich in lean protein sources, including protein smoothies."
3. "Get plenty of sleep," Dr. Apovian concludes. "Amongst other health benefits, this gives the body time to repair and rebuild the muscles."