How much to eat as you get older? 5 things to consider about your changing calorie needs, and what you need to maintain a healthy diet

As individuals age, their bodies undergo various changes, including a shift in nutritional requirements. One of the most significant changes is in the number of calories needed for maintaining weight and proper bodily functions. The size of a person's body plays a crucial role in determining their calorie needs. According to Herman Pontzer, a professor of evolutionary anthropology at Duke University, the larger a person is, the more calories they require. However, age is also a significant factor. While babies and children require fewer calories than adults due to their smaller size, their calorie needs relative to body size may be higher as they are in a phase of growth and development.

Physical activity is another factor that influences calorie needs. The more physically active a person is, the more calories they burn. Anna Maria Siega-Riz, a nutrition professor at the University of Massachusetts Amherst, states that an inactive 40-year-old man weighing 200 pounds would need about 2,700 calories daily to maintain his weight and basic bodily functions. However, if the same man were an athlete training for a couple of hours each day, his calorie needs would increase to about 3,500 daily.

As people age, their daily calorie requirements change. Starting around age 19, calorie needs gradually decrease each year. This decrease is estimated at around 11 calories daily annually for men and seven for women. For instance, a 77kg woman who walks for 60 to 80 minutes each day would need 2,450 calories per day at age 20. However, by age 60, this would have dropped to 2,150, and 2,000 at 80. This decline in calorie burn typically becomes more noticeable in the sixties and beyond, possibly leading to weight gain or a reduced appetite. This age-related decrease in calorie expenditure is associated with the loss of muscle and the gain of fat, which burns fewer calories. Additionally, the brain, the body's most metabolically active organ, naturally shrinks in size and requires less energy as a person ages. People also tend to become less physically active as they grow older, resulting in fewer calories burned.