Guide to 'BMI'

What is BMI?
BMI is a useful measure of overweight and obesity. It is calculated from your height and weight. BMI is an estimate of body fat and a good gauge of your risk for diseases that can occur with more body fat. The higher your BMI, the higher your risk for certain diseases such as heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems, and certain cancers.
How is BMI Classified?
BMI Weight Status
Below 18.5 Underweight
18.5 – 24.9 Normal or Healthy Weight
25.0 – 29.9 Overweight
30.0 and Above Obese
How good is BMI as an indicator of body fatness?
The correlation between the BMI and body fatness is fairly strong but even if 2 people have the same BMI, their level of body fatness may differ. In general,
  • At the same BMI, women tend to have more body fat than men.
  • At the same BMI, Blacks have less body fat than do Whites, and Asians have more body fat than do Whites
  • At the same BMI, older people, on average, tend to have more body fat than younger adults.
  • At the same BMI, athletes have less body fat than do non-athletes.
  • The accuracy of BMI as an indicator of body fatness also appears to be higher in persons with higher levels of BMI and body fatness. While, a person with a very high BMI (e.g. 35 kg/m2) is very likely to have high body fat, a relatively high BMI can be the results of either high body fat or high lean body mass (muscle and bone). A trained healthcare provider should perform appropriate health assessments in order to evaluate an individual's health status and risks.
  • What are the health consequences of obesity?
    People who are obese are at increased risk for many diseases and health conditions, including the following:
    • All-causes of death (mortality)
    • High blood pressure (Hypertension)
    • High LDL cholesterol, low HDL cholesterol, or high levels of triglycerides (Dyslipidemia)
    • Type 2 diabetes
    • Coronary heart disease
    • Stroke
    • Gallbladder disease
    • Osteoarthritis (a breakdown of cartilage and bone within a joint)
    • Sleep apnea and breathing problems
    • Chronic inflammation and increased oxidative stress
    • Some cancers (endometrial, breast, colon, kidney, gallbladder, and liver)
    • Low quality of life
    • Mental illness such as clinical depression, anxiety, and other mental disorders
    • Body pain and difficulty with physical functioning