Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Quick Facts



The Manual's Editorial Staff

Last full review/revision Dec 2019| Content last modified Dec 2019
Click here for the Professional Version
Get the full details
Topic Resources

What is obesity?

Obesity is having too much body fat. Obesity causes health problems. The fatter you are, the higher your risk of health problems.

Obesity can cause problems in almost any organ.

What causes obesity?

Obesity is caused by taking in more calories than your body needs. Diet, genes, lifestyle, and use of certain drugs are some factors in obesity.

The following increase your chance of being obese:

What are the symptoms of obesity?

Obesity may cause symptoms besides looking overweight. You may have:

  • Trouble breathing

  • Snoring

  • Skin problems including stretch marks

  • Joint and back pain

How can doctors tell if I am obese?

Doctors can tell if you're obese by:

  • Calculating your BMI (body mass index)

  • Measuring how thick the fat is on your waist and on the back of your upper arm

  • Sometimes doing a test that measures how much fat is in your whole body (body composition test)

Your BMI is your weight (in kilograms) divided by your height (in meters). You're obese if your BMI is 30 or higher. You're overweight if your BMI is over 25.

Doctors may also:

How do doctors treat obesity?

Obesity is much easier to prevent than treat. Once you gain weight, your body resists losing weight. For example, when you go on a diet, you feel hungrier and burn less energy when you’re resting.

Doctors treat obesity by helping you change some of your habits:

  • Eat healthier foods (high in fiber, low in sugar)

  • Put smaller portions on your plate so you're not tempted to eat as much

  • Eliminate high-calorie drinks, such as soda, juice, or alcohol

  • Exercise more and be more active (for example, take the stairs instead of the elevator, or walk instead of driving or taking the bus)

Going to group meetings with other people trying to lose or control their weight may help you keep your healthy eating and exercise habits on track.

For people with a lot of weight to lose, doctors may offer:

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version


Others also read

Test your knowledge

Postpartum Depression
Postpartum depression is a feeling of extreme sadness and related psychologic disturbances after delivery of a baby. Although it is common to feel sad or miserable within 3 days of delivery (the baby blues), these feelings usually go away within 2 weeks. Postpartum depression is a more serious mood change. Women in which of the following groups are at increased risk for this condition?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID