Interpretations of scientific data about overweight and obesity have differed because criteria for these terms have varied over time, from study to study, and from one part of the world to another. National and international organizations are now on support of the use of a Body Mass Index (BMI) of 30 or greater to identify obesity. These Body Mass Index (BMI) cut-points are only a guide for the identification and treatment of overweight and obese individuals and allow for the comparison across populations and over time. However, the health risks associated with overweight and obesity are part of a continuum and do not conform to rigid cut-points. There are multiple factors that can be used to determine how much risk a particular person is for ill health. People need to not only have weight awareness, but also have an awareness to their other physical, genetic and medical characteristics.
Body Mass Index (BMI)
Body Mass Index (BMI) is a common measure expressing the relationship (or ratio) of weight-to-height. It is a mathematical formula in which a person's body weight in kilograms is divided by the square of his or her height in meters (i.e., wt/ht). The Body Mass Index (BMI) is more highly correlated with body fat than any other indicator of height and weight.
Individuals with a Body Mass Index (BMI) of 25 to 29.9 are considered overweight, while individuals with a Body Mass Index (BMI) of 30 or more are considered obese or have obesity.
How is BMI interpreted?
According to the NIH Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, all adults (aged 18 years or older) who have a Body Mass Index (BMI) of 25 or more are considered at risk for premature death and disability as a consequence of overweight and obesity. These health risks increase even more as the severity of an individual's obesity increases
Waist circumference is a commonly used measure to assess abdominal fat content. The presence of excess body fat in the abdomen, when out of proportion to total body fat, is considered an independent predictor of risk factors and ailments associated with the obese weight or obesity.
There are limitations to its use because of a persons build or body structure. For example, if a person has short stature (under 5 feet in height) or has a Body Mass Index (BMI), of 35 or above, waist circumference standards used for the general population may not apply. Undesirable waist circumferences differ for men and women. Men are at increased health risks that have a waist measurement greater than 40 inches (102 cm) and women are at risk that have a waist measurement greater than 35 inches (88 cm).
Although waist circumference may not be the best independent indicator of risks, it was shown in 2003 to have a strong correlation to total health care charges.
Waist-to-hip ratio (WHR)
Waist-to-hip ratio (WHR) is the ratio of a person's waist circumference to hip circumference. This measurement is mathematically calculated as the waist circumference divided by the hip circumference. For most overweight people, carrying extra weight around their waist increases health risks more than carrying extra weight around their hips or thighs. Remember these types of measurements of body fat storage locations (waist circumference, waist to hip ratios) are not as significant as the overall picture of a persons total body fat quantity. Overall, obesity and morbid obesity are better indicators of increased risk than body fat storage locations or waist-to-hip ratio.
How can a waist-to-hip ratio help us interpret risk?
For both sexes, men and women, a waist-to-hip ratio of 1.0 or higher is considered ‘at risk' or in the danger zone for undesirable health consequences, such as heart disease and other ailments connected with being overweight or obese. This should help to make us more weight aware.
What is a goal waist-to-hip ratio?
For men, a ratio of .90 or less is considered safe.
For women, a ratio of .80 or less is considered safe.