Obesity is defined as an abnormally high proportion of body fat. Obesity occurs when calorie intake is consistently greater than the number of calories burned through activity and basic metabolic processes.

Several factors can influence obesity, including:

  • Genetic tendency
  • Eating habits
  • Activity level
  • Biologic factors (such as the amount and activity of certain chemicals in the body)
  • Medications (such as corticosteroids, antidepressants, and antipsychotics)
  • Underactive thyroid gland
  • Cushing's disease
  • Polycystic ovary syndrome
  • Fröhlich's syndrome
  • Prader-Willi syndrome
  • Laurence-Moon-Biedl syndrome

According to the World Health Organization, there are more than 300 million obese adults and 1.1 billion overweight people worldwide. And this number continues to rise. A similar pattern is apparent in the US. According to data from the Center for Disease Control (CDC), in 2006, 66.3% of adults age 20 and over are overweight, while approximately 30% are obese. (Overweight and obese are defined as a body mass index [BMI] greater than or equal to 25 and 30, respectively.)

Further, the number of American children who are overweight also continues to rise. Among Americans between the ages of 6-19, approximately 15% are overweight as of 1999-2000—or triple what the percentage was from 1980. (Overweight among children is based on BMI-for-age growth charts.) A combination of genetic factors, poor eating habits, and low activity levels accounts for the vast majority of the overweight and obesity in the United States.

Obesity can lead to other health problems, such as:

  • Decreased energy
  • High blood pressure
  • Heart disease and stroke
  • Type 2 diabetes
  • Gallstones
  • Worsening arthritis symptoms
  • Increased risk of certain cancers
  • Blood clots
  • Skin breakdown and infections
  • Gout
  • Infertility
  • Sleep apnea
  • Poor self-image
  • Depression