Having a healthy weight is important because there are health risks by being either underweight or overweight.
Undereweight people have a higher risk of developing health problems like brittle bones (osteoporosis), infertility (can’t get pregnant) and have a higher risk of getting infections. Underweight is often caused by eating disorders like anorexia and bulimia and illnesses such as cancer.
Overweight and obese (very overweight) people have a higher risk of developing a wide range of illnesses and conditions including type 2 diabetes, coronary heart disease and stroke, high blood pressure, some types of cancer (breast, endometrial, colon, prostate and kidney) and other negative health conditions.
Childhood obesity affects growth and development, and contributes to long term health problems. Young people who are overweight may also not feel good about themselves, which can affect their school performance and how they get along with other children. They may also be bullied and made fun of because of their weight.
A person’s weight is determined by the energy they take in (the food they eat) and the energy they put out (how active they are). Energy is measured in calories. The body requires a minimum number of calories to stay alive (i.e., to breathe and pump blood). As people get older, they need fewer calories or less food to sustain life. The body also requires sufficient calories to digest food and support the basic tasks of living, such as dressing, eating, and bathing as well as any physical activity such as walking, climbing stairs, exercising, working, harvesting or playing sports.
When people continue to take in more food energy than they burn each day, they will gain weight. When people are a healthy weight, they have achieved the right balance between “energy in” and “energy out”.