Fitness Not Fatness More Important to Health (cont.)

Changing to a healthy diet means cutting back on high-fat food and on starchy carbs. It means eating a balanced diet that includes protein, whole grains, vegetables, fruit, fiber, and, yes, some healthy fats. People who do this, and who get moderate exercise, can lose body fat and gain lean muscle.

"The studies suggest that if a 300-pound person drops 30 pounds, that person will have substantial reduction in several risk factors," the CDC's Gregg says. "And also that person will probably see an improvement in physical function and musculoskeletal problems and reduce his or her risk of osteoarthritis. And there would be a whole effect on health-related quality of life that is independent of these risk factors."

America Has an Eating Disorder

People with eating disorders have a distorted body image. They think they are fat even though they are dangerously thin. They are disgusted by fat. They exercise not for health, but to burn away calories. They weigh themselves not to check on their health, but to see how much weight they have lost. They starve themselves on crash diets until their brains rebel, forcing them to binge. The guilt makes them even harder on themselves.

Americans, Campos argues, have a collective eating disorder: We see normal people as fat. We are so disgusted by fat that the only perfectly acceptable prejudice is prejudice against people who are overweight or obese. We go on all kinds of crash diets, then feel guilty for binging on fast food. We are obsessed with weight, to the detriment of our health.

"The emaciated anorexic who looks in the mirror and says, 'I am fat' -- she is just working out the logical consequence of how we have demonized body fat in this culture," Campos says. "It is astonishing what is considered fat in this society."

According to Census data, the average American woman is about 5'4" tall and weighs a little more than 150 pounds. Her body-mass index or BMI -- a measure of weight adjusted for height -- is 26.3, which puts her in the "overweight" category. Yet she's leaner than half the population.

Campos criticizes those who argue that healthy body mass is between 18 and 21.9 BMI -- "for the average woman 5'4" tall, this is between 108 and 127 pounds," he says. "People flinch if you even say the word fat. It is seen as a poison. We see the elimination of fat as desirable. That is eating-disordered thinking. The difference between fashionable thinness and anorexia is whether you have been hospitalized or not."

"Let's focus on what people can do -- which is eat a healthy diet and improve fitness."

People come in all shapes and sizes. Yet we think one size should fit all -- and that size is thin.

"We have turned into a disease the fact that there is a huge variation in normal body mass," Campos says. "There is a huge number of people who are physically active and have nothing wrong with them in terms of anything measurable. They are being 'pathologized' because of this ridiculously narrow definition of what health means."

Blair says Cooper Institute studies show people at much higher BMIs than 25 can be quite fit -- although he stresses that extremely obese people, with a BMI of 45 or more, are almost never fit.

"We find that around half of obese individuals -- those with BMI of 30 or more -- about half do well enough on a maximal exercise test to get out of our 'low-fit category,'" Blair says. "Not only is it possible to be fit and fat, a substantial proportion of fat people are fit. I suspect that 15%-20% of normal-weight people are unfit. I'd like to shift the focus away from BMI."

BMI is an excellent tool for epidemiologists looking at weight across a population. For example, BMI quite accurately shows that the heaviest people are at the highest risk of diabetes.

But on an individual basis, it can yield some absurd results. For example, Campos notes, more than half of the players in the National Football League have a BMI of over 30 -- making them "obese." This includes more than three-fourths of the league's linebackers and tight ends. And nearly all of the league's quarterbacks fall into the "overweight" category.

"It is silly for a doctor to just look at someone's BMI number and recommend weight loss," Blair says. "Suppose you have a person with a BMI of 30 or 31, who doesn't smoke, who eats a diet high in fruit and vegetables, who has good [cholesterol] levels, and who runs a mile every day. Do you tell that person to lose weight? Some fanatics would say yes, you've got to get that BMI down. I think that is silly."

Getting Fit

Just because it's possible to be heavy and fit doesn't mean that gaining body fat is a good thing. It is not.

"To normalize being fat as healthy and appropriate is not the answer to the problem," Valone says. "To move away from obsessing with thinness to normalizing fatness is substituting one problem for another."

But telling everyone who's overweight or obese that they're bad unless they get thin isn't helpful.

"If shaming fat people about their bodies made people thin, there would be no fat people in America," Campos says. "If dieting made people thin, there would be no fat people in America."

Blair says we should face up to the facts.

"After all, we don't have very effective methods for weight loss," he says. "Let's focus on what people can do -- which is eat a healthy diet and improve fitness. If everybody took three 10-minute walks a day, ate better, and consumed no more than moderate amounts of alcohol, they would be healthier whether they lost weight or not."

Haskell stresses a balanced approach.

"Early on, if an individual has a tough time losing weight, I would suggest they not focus on weight loss but focus on 30 to 40 minutes of moderately intense activity on most days," he says. "If they focus on that, they may see some weight or body composition changes. You may not lose a lot of weight, but you may see a smaller belt size. But you have to eat fewer calories, too."

Take, for example, a man who weighs 220 pounds, consumes 3,000 calories a day, and gets no exercise.

"If that person increased his activity with a good walk every day after work and reduced to 2,500 calories intake, he will produce a 1,000-calorie-a-day negative balance -- that is two pounds a week," Haskell calculates. "He won't lose two pounds every week, but if he does it for 10 weeks he will lose 20 pounds. And that is hard to do by just activity or dieting alone. Doing each moderately can have a sustained effect."