Obesity Overview

In adults aged 20 years and older, obesity is defined as having a body mass index (BMI) of 30 or more. People with a BMI of 40 or more have severe obesity. This is a common condition among adults in the United States—data from the 2017–2018 National Health and Nutrition Examination Survey suggest that 42.4% of adults have obesity and 9.2% have severe obesity.¹

Severe obesity is slightly more common in women than in men.¹ In addition, weight gain is a common occurrence during menopause as metabolism and hormone levels change.^{2 , 3}

People with obesity have a higher risk of several conditions, including hypertension, dyslipidemia, obstructive sleep apnea, osteoarthritis, atherosclerotic cardiovascular disease, metabolic dysfunction-associated steatotic liver disease, and some types of cancer (e.g., breast cancer).⁴ Obesity can also increase the risk of polycystic ovary syndrome in women.^{4 , 5} Because obesity can cause issues with ovulation and menstruation, women with obesity may have difficulty conceiving. In pregnant women, obesity can increase the risk of gestational diabetes and preeclampsia, and it may also put infants at a higher risk of conditions like asthma and type 2 diabetes once they reach adulthood.⁶

Ongoing research seeks to address a number of different aspects of obesity, including how obesity affects people across different life stages. More information is needed about the effects of obesity in childhood, during pregnancy and menopause, and in older individuals.

NIH established the Obesity Research Task Force to better understand the factors that contribute to obesity and to develop new methods for prevention and treatment. This task force allows many of NIH’s Offices, Centers, and Institutes to collaborate on obesity research and investigate the genetic, environmental, and behavioral factors that lead to this condition; one of the participating centers is the Office of Research on Women’s Health (ORWH).⁷ Visit the Obesity Research Task Force’s website for information on current and past funding opportunities for obesity research and the dates of upcoming meetings and workshops.