Hormonal changes are one of the main reasons that women tend to lose more muscle as they approach menopause. Diet and exercise also play a role.12 On average, adults lose 3 to 8 percent muscle every decade after age 30.13,14 By the time you reach 80, you may have about 30 percent less muscle than you had at age 20.15,16 Muscle loss over time can lead to slower RMR, increased fat, weight gain, weakness, and fractures.17
Focusing on being healthy means getting about 30 minutes of moderate exercise every day. This level of exercise can keep your heart healthy and work on things like lowering your cholesterol and/or blood pressure. This is a great place to start if you're getting into exercise after a long break. There's no reason you can't start here and progress to more intense goals as you build strength and endurance.
Between desk jobs, commutes, and family activities, many 40-somethings don’t have a lot of free time to work out. But it’s important -- for your weight and your overall health -- to fit in at least 2 1/2 hours of moderate physical activity (like brisk walking or light yard work) every week. Pencil times in to your calendar, and make them a priority.