To Thine Own Self Be True

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To Thine Own Self Be True

November 27th 2007 -
A Cornell University study, sponsored by the National Institutes of Health, will appear in the December 8th issue of the journal Eating Behaviors. Researchers asked 320 college students what they considered their ideal body weight. They were dismayed to find that sixty percent of the men and fifty percent of the women classified as being overweight by body mass index (BMI) named a weight that would still fall into the overweight category.

I applaud those young men and women for recognizing what today’s medical profession does not: people come in assorted sizes. When two-thirds of the population is defined as being sick, something is seriously wrong with the definition.

A sizable percentage of people are physically incapable of achieving an ideal body weight as it is currently defined. BMI is simply one's weight divided by one’s height (technically, one's weight in kilograms divided by the square of one's height in meters). If the result is greater than 25 the person is classified as “overweight” and if it is greater than 30 the individuals is considered “obese”.

BMI does not take into account bone size or muscle development. It cares nothing about body fat content. As a result, most highly trained athletes fall into the overweight classification and many are defined as obese. The only way many women will be able to achieve their “ideal” body weight is by developing severe muscle atrophy and osteoporosis.

The suggestion that a BMI of less than 25 is “healthy” and a BMI over 25 is not is purely a matter of conjecture. It is not a proven scientific fact. Even if it could be proven that people with a BMI of 25 are statistically more likely to live longer than those with a BMI over 25, which is doubtful, there is not one shred of evidence that an individual with a natural body habitus that results in a BMI of 28 will be healthier and live longer if he or she loses enough bone and muscle mass to achieve a BMI of 25.

There are legitimate ways to determine whether you are at risk of developing health challenges because you are carrying excessive body fat, but the BIM is not one of them. Some techniques used to determine whether you are carrying too much body fat are difficult to perform and some are costly. One of the best is to calculate your waist to hip ratio by dividing your waist size by that of your hips. The test is simple, it is inexpensive, and it is very good at predicting your risk of developing diabetes and heart disease.

The next time you hear or read about the obesity epidemic remember the Cornell undergraduates and recognize that the $40 billion/year weight loss industry promoting BMI as an indication that you need their services does not have your best interest at heart. If you are concerned about your body size as it relates to your health determine your waist/hip ratio and take appropriate steps to improve it if you find that you are in the upper 2 or 3 quintiles. (See lists below.)

Dale Peterson, M.D.

Men W/H ratios

Quintile Waist/Hip Ratio
1st <0.906
2nd 0.907-0.941
3rd 0.942-0.973
4th 0.974-1.009
5th >1.009

Women W/H Ratios

Quintile - Waist/Hip Ratio
1st <0.802
2nd 0.803-0.841
3rd 0.842-0.878
4th 0.879-0.920
5th >0.920