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Basics

• Summary
• Start Here
• Diagnosis and Tests
• Prevention and Risk Factors
• Treatments and Therapies

Learn More

• Related Issues
• Specifics
• Genetics

See, Play and Learn

• Health Check Tools

Research

• Statistics and Research
• Clinical Trials
• Journal Articles

Resources

• Reference Desk
• Find an Expert

For You

• Children
• Teenagers
• Men
• Women
• Patient Handouts

Summary

Obesity means having too much body fat. It is different from being overweight, which means weighing too much. The weight may come from muscle, bone, fat, and/or body water. Both terms mean that a person's weight is greater than what's considered healthy for his or her height.

Obesity happens over time when you eat more calories than you use. The balance between calories-in and calories-out differs for each person. Factors that might affect your weight include your genetic makeup, overeating, eating high-fat foods, and not being physically active.

Obesity increases your risk of diabetes, heart disease, stroke, arthritis, and 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.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases

Start Here

• Defining Overweight and Obesity (Centers for Disease Control and Prevention)
• Healthy Weight (Department of Health and Human Services, Office on Women's Health)
• Obesity (Mayo Foundation for Medical Education and Research)

Diagnosis and Tests

• Assessing Your Weight and Health Risk (National Heart, Lung, and Blood Institute)
• Body Mass Index Table (National Heart, Lung, and Blood Institute)
• Obesity Screening (National Library of Medicine) Also in Spanish
• Screening for and Management of Obesity in Adults (U.S. Preventive Services Task Force) - PDF

Prevention and Risk Factors

• Aim For a Healthy Weight (National Heart, Lung, and Blood Institute)
• Balance Food and Activity (National Heart, Lung, and Blood Institute) Also in Spanish

Treatments and Therapies

• Weight Control: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
• Weight Loss Surgery: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish

Related Issues

• COVID-19: Obesity (Centers for Disease Control and Prevention) Also in Spanish
• Disability and Obesity (Centers for Disease Control and Prevention) Also in Spanish
• Normal Weight Obesity: A Hidden Health Risk? (Mayo Foundation for Medical Education and Research) Also in Spanish
• Obesity (Hormone Health Network) Also in Spanish
• Obesity and Anesthesia (American Society of Anesthesiologists)
• Obesity and Cancer Risk (National Cancer Institute) Also in Spanish
• Obesity and Your Digestive Health (American College of Gastroenterology) - PDF
• Staying Active at Any Size (National Institute of Diabetes and Digestive and Kidney Diseases)

Specifics

• Health Risks of Overweight and Obesity (National Institute of Diabetes and Digestive and Kidney Diseases)
• Mind/Body Health: Obesity (American Psychological Association) Also in Spanish
• Obesity Hypoventilation Syndrome (National Heart, Lung, and Blood Institute)
• Understanding Adult Overweight and Obesity (National Institute of Diabetes and Digestive and Kidney Diseases)
• Weight Management and Healthy Living Tips (National Institute of Diabetes and Digestive and Kidney Diseases)

Genetics

• Congenital leptin deficiency: MedlinePlus Genetics (National Library of Medicine)
• Leptin receptor deficiency: MedlinePlus Genetics (National Library of Medicine)
• Proopiomelanocortin deficiency: MedlinePlus Genetics (National Library of Medicine)

Health Check Tools

• Calculate Your Body Mass Index (National Heart, Lung, and Blood Institute) Also in Spanish

Statistics and Research

• Cancer and Obesity (Centers for Disease Control and Prevention) Also in Spanish
• Diabetes Interactive Atlas (Centers for Disease Control and Prevention)
• Obesity Prevalence Maps (Centers for Disease Control and Prevention)
• Overweight and Obesity Statistics (National Institute of Diabetes and Digestive and Kidney Diseases)

Clinical Trials

• ClinicalTrials.gov: Obesity (National Institutes of Health)

Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)

• Article: Changes in Body Composition and Cardiometabolic Health After Detraining in Older...
• Article: Obesity is a Major Risk Factor for Hospitalization in Community-Managed COVID-19...
• Article: Obesity and covid-19: a reflection on the relationship between pandemics.
• Obesity -- see more articles

Reference Desk

• Weight Management and Obesity: General Information and Resources (Food and Nutrition Information Center) - PDF

Find an Expert

• Find a Nutrition Expert (Academy of Nutrition and Dietetics)
• Find an Obesity Medicine Clinician (Obesity Medicine Association)
• National Heart, Lung, and Blood Institute
• National Institute of Diabetes and Digestive and Kidney Diseases

Children

• Obesity in Children: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish

Teenagers

• Dealing With Feelings When You're Overweight (For Teens) (Nemours Foundation) Also in Spanish

Men

• Belly Fat in Men: Why Weight Loss Matters (Mayo Foundation for Medical Education and Research) Also in Spanish

Women

• Belly Fat in Women: Taking -- and Keeping -- It off (Mayo Foundation for Medical Education and Research) Also in Spanish
• Pregnancy and Obesity: Know the Risks (Mayo Foundation for Medical Education and Research)

Patient Handouts

• Body mass index (Medical Encyclopedia) Also in Spanish
• Health risks of obesity (Medical Encyclopedia) Also in Spanish
• Obesity (Medical Encyclopedia) Also in Spanish
• Obesity hypoventilation syndrome (OHS) (Medical Encyclopedia) Also in Spanish