Health Topic

Obesity

Read about the causes of obesity and find out what you can do to decrease your risk of its associated health issues.

Reviewed Reviewed by a registered pharmacistGeneral information

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About 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.

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

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 fat around your abdomen (belly) rather than your hips, increases your risk for weight-related health problems.

Having a larger body size can make your heart work harder, put extra pressure on your joints, and may increase your risk for many health conditions, including:

  • Type 2 diabetes.
  • Heart disease.
  • High blood pressure.
  • Stroke.
  • Metabolic syndrome.
  • Osteoarthritis.
  • Sleep apnea.
  • Pregnancy problems.
  • Fertility problems.
  • Some cancers.

If you have obesity, losing even 5 to 10% of your weight can delay or prevent some of these diseases. For example, that means losing 10 to 20 pounds if you weigh 200 pounds.

Treatment plans for obesity may depend on your overall weight, other health conditions, and your willingness to participate in a weight-loss plan.

Your provider can tell you what a healthy weight is for you, help you set goals, and give you tips on how to lose weight. They may refer you to other providers that specialize in nutrition or weight loss to help you make realistic goals and provide support.

Possible treatments may include:

  • Dietary changes and exercise goals to help you learn how to adopt healthy nutrition, exercise, and lifestyle changes to lose weight safely and keep it off long term.
  • Counseling or support groups can give you encouragement and help you understand what's behind weight changes.
  • Weight-loss medicines to treat obesity.
  • Weight loss procedures or surgery if you have severe obesity or serious obesity-related health problems and have not been able to lose enough weight.

A healthy lifestyle that includes healthy eating patterns and regular physical activity can help you lose weight and lower your chance of developing complications related to obesity.

It sits within Food and Nutrition and Metabolic Problems.

The lead U.S. institute for this subject is the National Institute of Diabetes and Digestive and Kidney Diseases.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Obesity

14,715 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

Start Here

  • About ObesityCenters for Disease Control and Prevention
  • ObesityMayo Foundation for Medical Education and Research
  • ObesityEndocrine Society

Diagnosis and Tests

Treatments and Therapies

Prevention and Risk Factors

Related Issues

Genetics

Statistics and Research

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Obesity. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Obesity, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.