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 disease to explain why illnesses happened. Doctors who washed their hands between patients drew scorn from colleagues for their fastidiousness. Surgery without anesthetics or blood typing was frequently fatal. It was also the year that the Body Mass Index, or BMI, came into being. Unlike other outdated medical practices, BMI still remains in use.
The calculations for BMI involve only height and weight. Measuring the relationship between these two characteristics against a set of ideal characteristics theoretically gives an idea of an individual's overall health. For people with moderate muscle mass, this relationship can indicate overweight or obesity. However, because BMI fails to take gender, age, fitness or body composition into account, millions of healthy people wind up in the "overweight" or "obese" categories.
At the extremes of physical fitness, BMI is not only inaccurate, it's absurd. Many professional athletes are overweight or obese according to BMI figures. NFL quarterback Tom Brady falls in the middle of the overweight category with a BMI of 27.5, while his shorter counterpart Drew Brees edges dangerously close to obesity with a BMI of 28.5. Tony Romo has even less wiggle room with his BMI of 29. One...