What Are Overweight and Obesity?

The terms “overweight” and “obesity” refer to a person’s overall body weight and where the extra weight comes from. Overweight is having extra body weight from muscle, bone, fat, and/or water. Obesity is having a high amount of extra body fat. The most useful measure of overweight and obesity is the body mass index (BMI). BMI is based on height and weight and is used for adults, children, and teens. For more information about BMI, see “How Are Overweight and Obesity Diagnosed?”

Millions of Americans and people worldwide are overweight or obese. Being overweight or obese puts you at risk for many diseases and conditions. The more body fat that you carry around and the more you weigh, the more likely you are to develop heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems, and certain cancers.

A person’s weight is a result of many factors. These factors include environment, family history and genetics, metabolism (the way your body changes food and oxygen into energy), behavior or habits, and other factors.

Certain things, like family history, can’t be changed. However, other things—like a person’s lifestyle habits—can be changed. You can help prevent or treat overweight and obesity if you:

  • Follow a healthful diet, while keeping your calorie needs in mind
  • Are physically active
  • Limit the time you spend being physically inactive

Weight loss medicines and surgery also are options for some people who need to lose weight if lifestyle changes don’t work.

Outlook

Reaching and staying at a healthy weight is a long-term challenge for people who are overweight or obese. But it also can be a chance to lower your risk of other serious health problems. With the right treatment and motivation, it’s possible to lose weight and lower your long-term disease risk.

May 2008

Key Points

  • The terms “overweight” and “obesity” refer to a person’s overall body weight and where the extra weight comes from. Overweight is having extra body weight from muscle, bone, fat, and/or water. Obesity is having a high amount of extra body fat.
  • Millions of Americans and people worldwide are overweight or obese.
  • Being overweight or obese puts you at risk for many diseases and conditions, including heart disease, high blood pressure, type 2 diabetes, gallbladder disease, breathing problems, and certain cancers.
  • A person’s weight is the result of many factors, including environment, family history and genetics, metabolism (the way your body changes food and oxygen into energy), behavior or habits, and other factors.
  • For most people, overweight and obesity are caused by not having energy balance. The amount of calories you get from food and drinks is energy IN. The amount of energy your body uses daily is energy OUT. To maintain a healthy weight, energy IN and energy OUT should balance over time.
  • Overweight and obesity are calculated using the body mass index (BMI). BMI is an estimate of body fat and a good gauge of your risk for diseases that occur with more body fat. Adults can calculate their BMI using the National Heart, Lung, and Blood Institute’s online calculator, or your health care provider can calculate your BMI.
  • Children’s BMI is calculated based on growth charts for their age and sex. This is called BMI-for-age percentile. For more information, go to the Centers for Disease Control and Prevention’s BMI-for-age calculator.
  • Treatment for overweight and obesity includes lifestyle changes. These changes mean cutting back on calories, following a healthy eating plan, being physically active, and making behavioral changes.
  • When lifestyle changes aren’t enough, other treatment options for some people are weight loss medicines and surgery.
  • To manage weight and prevent unhealthy weight gain, adults should aim for 60 minutes of moderate-to-vigorous intensity physical activity most days of the week. To keep up weight loss, aim for 60 to 90 minutes of daily moderate-intensity physical activity.
  • Children and teens should strive for 60 minutes of physical activity a day.
  • Overweight and obesity in children and teens can be prevented with healthy food choices and more physical activity. Parents and families should create habits that encourage healthful food choices and physical activity early in a child’s life.