TCS Daily

'No Matter What the Data Say'

By Sydney Smith - May 29, 2003 12:00 AM

There's no escaping the assault against obesity that's being waged by American public health advocates. Secretary of Health and Human Services Tommy Thompson has threatened unspecified punishment for fast food companies who fail to offer healthy alternatives to their profitable products. Public advocacy lawyers are on the attack, so far with mixed success. Although the attempt to sue McDonald's for individual obesity failed and the attempt to ban Oreos was given up in the face of ridicule, others are considering action on the grounds that fast food is addicting and that restaurants don't warn us about the fat content of their food. But, as earnest as the anti-fat crusaders may be, they're ignoring an important front in the war on obesity - exercise.

For all the talk about carbohydrates versus fats, the truth is that weight gain and weight loss are simply a matter of energy balance. Take in more calories than you expend in the course of the day, and you'll gain weight. Expend more than you take in, and you'll lose weight. It only takes a few extra calories a day over the course of a year or two to cause a slow weight gain. It doesn't matter whether those extra calories come from an apple or from a cookie. Calories are calories. What's more, eating the same number of calories every day while performing less physical activity will also add the pounds. It's a delicate balance between input and output, and it isn't at all clear that excessive input is the primary cause of our obesity epidemic.

The average daily caloric consumption of Americans is not far from the recommended rates of 1800 to 2200 calories a day (depending on age and sex.) On the other hand, less than ten percent of schools set aside time for physical education each day, and less than 40 percent of adults engage in enough physical activity to confer health benefits. With numbers like that, our waist lines will continue to expand, no matter what we eat.

A recent study of teenagers' habits over the past twenty years supports this observation. Nutritionist Lisa Sutherland of the University of North Carolina at Chapel Hill looked at data from the CDC's National Health and Nutrition Examination Survey and Youth Risk Behavior Surveillance System, and the Department of Agriculture's Nationwide Food Consumption Survey, all of which have been following our national weight trends, activity trends, and food consumption trends for several years. She found that over the past twenty years, teenagers have, on average, increased their caloric intake by one percent. During that same time period, the percentage of teenagers who said they engaged in some sort of physical activity for thirty minutes a day dropped from 42 percent to 29 percent. Not surprisingly, teenage obesity over the twenty year period increased by 10 percent. The logical conclusion is that it isn't junk food that's making teenagers fat - it's their lack of activity.

This isn't the first study that has suggested the importance of exercise in the obesity equation. Consider the Pima Indians. The Pima Indians of Arizona have one of the highest rates of obesity in the world, while the Pima Indians of Mexico have very low rates - even though they eat on average the same number of calories a day. The difference? The Mexican Pimas spend twice as much time engaging in physical activity as American Pimas. Or consider the study of British twins which showed less body fat in twins who exercised compared to their less active siblings. And then there are the weight loss success stories. Study after study shows that those who lose weight and keep it off are those who exercise regularly.

Yet, nutrition experts expressed skepticism about the recent findings in teenagers. Dr. Nancy Krebs, the chair of the American Academy of Pediatrics' committee on nutrition told the Associated Press, "We are pretty sure they are eating too much, no matter what the data say." While the spokeswoman for the American Dietetic Association, JoAnn Hattner, put it more succinctly:

Accepting the conclusion that food is not a big part of the problem could take pressure off food companies to cut the calories they feed the nation, Hattner said.

"There is enough clamor throughout the country that we are getting corporations to change," Hattner said. "We need to continue that clamor."

But the data do matter. And the data suggest that clamoring at corporations isn't likely to make much of a dent in the obesity epidemic. Which leaves the question of who will be the next target of the crusaders when the assault on restaurants fails. Better make time for the gym, or it could be you.

The author is a family physician who has been in private practice since 1991. She is board certified by the American Board of Family Practice, and is a Fellow of the American Academy of Family Practice. She is the publisher of MedPundit.

TCS Daily Archives