As people age, their body composition gradually shifts — the proportion of muscle decreases and the proportion of fat increases. This shift slows their metabolism, making it easier to gain weight. In addition, some people become less physically active as they get older, increasing the risk of weight gain.
The good news is that weight gain can be prevented by choosing a lifestyle that includes good eating habits and daily physical activity. By avoiding weight gain, you avoid higher risks of many chronic diseases, such as heart disease, stroke, type 2 diabetes, high blood pressure, osteoarthritis, and some forms of cancer.