BMI Does NOT Determine Obesity

The obesity epidemic makes headlines daily as newscasters recite statistics about the dangers of excess body weight. Mexican food, movie popcorn and the all-American burger have all fallen under the disapproving glare of public health proponents. Experts inveigh against the dangers of carrying extra flab and warn that without drastic measures, the current generation of overweight kids will become the first generation to lead shorter lives than their parents. All too often, this hatred of fat transfers itself to a hatred of fat people.

With so many terrifying statistics about heart disease, type 2 diabetes, stroke and organ dysfunction related to obesity, it's easy to conclude that any excess weight imperils people who carry it. To some extent, the concerns are justified; these risks are real at the highest ends of the weight spectrum. There's little question that significant excess weight contributes to serious health problems. Extreme obesity can also impede quality of life as well as its quantity.

However, the foundation on which the notion of obesity rests -- body mass index, or BMI -- is fundamentally flawed. Without a clear vision of what constitutes overweight and obesity, it's impossible to assert that any amount of excess weight is bad. On the contrary, studies of the health consequences of significantly low body weight reveal that too little weight is as lethal as extreme obesity and considerably more dangerous than having a moderately high BMI. These statistics also look less alarming under more careful scrutiny, as many studies fail to differentiate between a few extra pounds and a few hundred of them.

The Myth of BMI

In 1850, doctors had no antibiotics, nor did medical personnel have a germ theory of dis...

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...xtra pounds is healthier than being underweight by a similar amount, the prevailing attitude is that no fat is good fat. The tool that medical professionals used as a yardstick has become an instrument of punishment for heavy people.

More realistic appraisals of the risks of excess fat are leading to changes within the medical establishment. While health care professionals' views are evolving on overweight and mild obesity, the public face of obesity is slower to change. Media outlets still focus on the obesity epidemic and its potential costs, unfairly stigmatizing any weight gain as a public health issue instead of a personal choice.

When strident warnings about the evils of butter or brownies grow too deafening, it's helpful to think of the state of medicine in 1850 and recall how times have changed. Eventually the world will catch up with modern medicine.