How Fat is Too Fat?

Body Mass Index
A report by the National Institutes of Health (NIH) (1998) proposed a revised set of guidelines for determining who is overweight and obese based on the Body Mass Index (BMI). Your BMI is calculated by dividing your weight in kilograms by your height in meters squared. Those with a BMI of 25 or below are considered healthy, those with a BMI which is >25 and <30 are overweight, and those with a BMI of 30 or more are obese. Some researchers (including ELS) feel that a BMI of 25 is too stringent of a guideline to use for older adults.

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By current estimates using a BMI of 25, 97 million adult Americans or about 55% are overweight or obese. Being overweight increases the risk for many common chronic diseases, including heart disease, certain cancers, stroke, non-insulin dependent diabetes, and atherosclerosis. Those who are obese have a lower life expectancy and many more health problems.

Importantly for those who are older and overweight, several studies indicate that the relationship between obesity and mortality risk decreases with age. Bender and colleagues (JAMA, 1999) found that the relative risks of death do not increase with BMI in older adults. No excess mortality was found for those age 50 or older who had a BMI that ranged between 25 to 32 kg/m2. Other studies find that the age at which a person becomes obese affects their relative health risks. For a similar degree of obesity, those who become obese before age 40 face greater health risks than those who become obese after age 40.

Visit the BMI Center at Shapeup America! to calculate your Body Mass Index.

Body Shape Matters
Clearly BMI is not the whole story. Another factor influencing obesity-related health risks is the distribution of fat on your body. It is better to resemble a pear than an apple. Women tend to have more buttock and hip fat (pear shape) while men have more abdominal fat (apple shape). The major complications of overweight are associated with increased abdominal fat.

Measure Your Waist
In addition to your height and weight to calculate your BMI, you should measure your waist. The health risks of being overweight increase for men with a waist measurement of more than 40 inches and for women with a waist of more than 36 inches (NIH, 1998). For every inch a man's stomach exceeds the size of his chest, he can deduct two years from his life. A "pot belly" provides glaring evidence that you are eating too much, exercising too little, or both. In general, the ratio of waist circumference to maximum hip circumference should be less than .95 in men and less than .85 in women for good health (Croft et al., 1995).