After age 40, human metabolism steadily slows down. But there are many ways to boost your metabolism. Boosting metabolism can often help burn calories, improve overall health and thus slow down the aging process.
Strength training can help grow muscle, and thus raise your metabolism. Aerobic exercise, especially high-intensity workout, can also help to boost your metabolism. Since human body uses water to burn calories, drinking more water can help prevent dehydration and maintain your metabolism. Although you need to eat a balanced diet, eating more protein-rich foods (such as lean meat and fish), can also help to boost your metabolism.