1. Home
  2. Health Information
  3. Weight Management
  4. Understanding Adult Overweight & Obesity

Understanding Adult Overweight & Obesity

View or Print All Sections

Definition & Facts

The terms “overweight” and “obesity” refer to body weight that is greater than what is considered healthy for a certain height.

A man and woman at home.

Factors Affecting Weight & Health

Many factors can affect your weight, leading to overweight or obesity. Some of these factors may make it easy for you to gain weight or regain weight you have lost.

Am I at a Healthy Weight?

Knowing your body mass index (BMI) and waist size helps tell if you have a healthy weight, overweight, or obesity. Gaining extra fat around the abdomen increases your risk for certain health problems.

Health Risks

Overweight and obesity may increase your risk for developing health problems, such as diabetes, heart disease, stroke, and certain cancers.

Eating & Physical Activity to Lose or Maintain Weight

Choosing a healthy eating plan that you can stay on for the long-term may help you lose weight. Being physically active may help you use more calories and maintain your weight loss.


Common treatments for losing weight include adopting a healthy eating plan, being physically active, and making other changes to your lifestyle. Other treatments include weight-loss medicines and weight-loss surgery, also called metabolic and bariatric surgery.

Clinical Trials

NIDDK conducts and supports clinical trials in many diseases and conditions, including overweight and obesity. The trials look to find new ways to prevent, detect, or treat disease and improve quality of life.


Obesity affects more than 1 in 3 adults in the United States. About 1 in 6 children and adolescents ages 2 to 19 are considered to have obesity in the United States. Another 1 in 3 adults is considered to be overweight. View the latest statistics.

Last Reviewed May 2023

This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by NIDDK is carefully reviewed by NIDDK scientists and other experts.

NIDDK would like to thank:
Kelly Costello Allison, Ph.D., University of Pennsylvania