Understanding Obesity

Obesity is defined as excess body fat. It is most often determined by measuring a person’s Body Mass Index (BMI), a ratio involving a person's weight and height.

Weight Category

Body Mass Index (BMI) Kg/m2


Less than 18.5

Normal Weight

18.5 - 24.9


25.0 - 29.9

Obesity Class I

30.0 - 34.9

Obesity Class II

35.0 - 39.9

Obesity Class III

More than 40

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There are exceptions to this standard. For example, a person at a healthy weight with a large percentage of body fat may be considered obese. This can be determined using a special medical scanner that measures body composition.Understanding Obesity

What causes obesity?

Obesity is often thought of as a disease caused by a sedentary lifestyle, meaning eating too many calories and not getting enough exercise. While this certainly contributes to the problem, it is not the only factor. Genetics and factors such as environment, culture, socioeconomic status and psychology also play a role.

Impacts of Obesity

Obesity often causes or worsens other medical conditions. The most common obesity-related medical conditions, or co-morbidities, include:

  • Coronary artery disease
  • Depression
  • Fatty liver disease
  • Gallbladder disease
  • GERD (reflux)
  • Hypertension (high blood pressure)
  • Hyperlipidemia (elevated cholesterol)
  • Infertility
  • Joint pain or arthritis
  • Obstructive sleep apnea
  • Stress urinary incontinence
  • Type 2 diabetes

Obesity also impacts lives in other ways, often causing relationship problems, discrimination in the workplace and economic problems such as lost wages and increased health care costs.