Obesity

Source: MedlinePlus Health Topics, U.S. National Library of Medicine

Last synced 8/4/2026Status: primary verified

What is obesity? Obesity is a disease that means having too much body fat. It is different from being overweight, which means weighing too much. Both terms mean that your weight is greater than what's considered healthy for your height. Body Mass Index (BMI) measures how much you weigh compared to how tall you are. An adult who has a BMI of 30 or more is considered to have obesity. Severe obesity is having a BMI of 40 or higher. Obesity increases your risk for many other diseases and health problems, especially if the extra body fat is carried around the waist. What raises your risk of obesity? Obesity happens over time from taking in more calories (through food and drinks) than used up from physical activity and daily living. Your body stores the extra calories as fat. The right balance between calories and activity is different for everyone. There are many different factors that can affect your body weight . Certain medicines or medical conditions may affect your weight. Other factors include your: Genetic makeup Eating habits Sex Race or ethnicity Physical activity level How is obesity diagnosed? To find out if you have obesity, your health care provider may: Ask about your health history , which may include reviewing your weight history, weight-loss efforts, and how physically active you are. Do a physical exam , which may include checking your height, weight, and vital signs , as well as listening to your heart and lungs. Order blood tests or other imaging tests , which may include checking any known health problems, as well as for other weight-related diseases and health conditions. Calculate your BMI , to check your risk for certain diseases. The higher your BMI, the higher your risk. BMI does not distinguish between fat, muscle, and bone mass. It may also overestimate body fat in athletes or those with a muscular build, or underestimate body fat in older persons, or others who have lost muscle. Check your waist size , since a large waistline, with more body

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This information is for general education and is not medical advice. Always talk to a licensed U.S. clinician about your situation, medications, or treatment decisions.