Test Your Knowledge

A person’s metabolic rate does not remain the same at all times. Certain events and activities may cause metabolism to decrease or increase. These include:

• Age. Due to changes in hormones and a reduced muscle-to-fat ratio, metabolism slows down as people age.
  
  
• Pregnancy and breastfeeding. To support the growth of a fetus, a pregnant woman must take in more calories when she is pregnant. Breastfeeding an infant also requires more calories. These events may increase a woman’s rate of metabolism.
  
  
• Exercise. Metabolism is increased after exercising. For how long it is increased depends on the individual as well as the duration and intensity of the exercise, but the boost can last for several hours. Strengthening the muscles also increases muscle mass, boosting the body’s muscle-to-fat ratio and further increasing metabolism.
  
  
• Eating habits. How frequently a person eats affects metabolism. When calories are scarce (e.g., when fasting), the body attempts to conserve energy by slowing down metabolism. When the body receives a steady stream of calories (e.g., frequent, small meals), it does not attempt to conserve energy as much. Thus, metabolism speeds up. Metabolism also increases for several minutes immediately after eating. Therefore, eating small, frequent meals burns fat much more quickly than skipping meals or fasting.