Obesity is a serious, chronic disease that can inflect substantial harm to a person's health. Overweight and obesity are not the same; rather they are different points on a continuum of weight ranging from underweight to being morbidly obese.

Patients are categorized as overweight and obese based upon their Body Mass Index (BMI), a useful body fat indicator that measures weight as it relates to height. In adults, a BMI from 18.5 to 24.9 is considered normal, while a BMI of more than 25 is considered overweight. The primary symptom of obesity is a BMI greater than 30, and morbidly obese if the BMI is 40 or greater.

When evaluating a child's weight, the BMI is measured and then plotted on a BMI for age percentile curve. A child is classified as overweight if his BMI for age percentile ranking is in the 85th to less than 95th percentile. The child is classified as obese if his BMI for age percentile ranking is greater than the 95th percentile. Learn more about childhood obesity and weight management for children and adolescents.


Obesity is a puzzling disease. How the body regulates weight and body fat is not well understood. On one hand, the cause appears to be simple: If a person consumes more calories than he expends as energy, then he will gain weight. However, on the other hand, obesity can be determined by a complex combination of risk factors such as:

  • Genetics — studies have shown that people can inherit a predisposition toward obesity.
  • Metabolic factors — metabolic and hormonal factors are not the same for everyone, but they play a role in determining weight gain.
  • Socioeconomic factors — poor women of lower social status are more likely to be obese than women of higher socioeconomic status. Obesity is also highest among minority groups, especially women.
  • Lifestyle choices — overeating, in conjunction with a sedentary lifestyle, contributes to obesity in children and adults.

Health effects

The negative health effects of obesity are far-ranging and significant. They include:

  • High blood pressure — additional fat tissue in the body needs oxygen and nutrients in order to live, requiring blood vessels to circulate more blood to the fat tissue. This increases the workload of the heart and leads to high blood pressure.
  • Diabetes — obesity is the major cause of Type 2 Diabetes, the most common form of diabetes. Even moderate obesity dramatically increases the risk of diabetes.
  • Heart disease — atherosclerosis (hardening of the arteries) occurs more often in obese people because fatty deposits build up in arteries that supply the heart, leading to chest pain and heart attacks. In addition, blood clots can cause strokes.
  • Cancer — overweight women have an increased risk for various cancers such as breast, colon, gallbladder and uterine. Overweight men have a higher risk of colon and prostate cancers.
  • Joint problems, including osteoarthritis
  • Sleep apnea and respiratory problems
  • Metabolic syndrome
  • Psychosocial effects

(888) 321-DOCS

Call to find the doctor that’s right for you.

Representatives are available 24 hours a day, seven days a week. If this is an emergency dial 911.

Online health risk assessments

Spend five minutes assessing your risk for breast cancer, diabetes, heart disease and more.