June 15, 2004 -- Are those super-sized fast food meals really to blame for the supersizing of America's kids? The debate continues, but new research offers some of the best direct evidence yet that they are at least part of the problem.
Researchers found that all teens tended to overeat when served a typical "extra-large" fast food meal, but normal-weight teenagers were more likely than overweight teens to make up for the overindulgence by eating less later on. The findings are reported in this week's Journal of the American Medical Association.
Overweight teens averaged a whopping 400 extra calories on days when they ate one meal at a fast food restaurant, says researcher Cara B. Ebbeling, PhD.
"Overweight kids tend to be less able to compensate for the extra calories in a fast food meal," she tells WebMD. "These findings provide a basis for how fast food could promote excess weight gain."
Fast food consumption in the U.S. has risen by 500% during the last three decades, while the number of children who are obese has tripled.
While many nutritionists say the growth in popularity of fast food is largely responsible for the obesity epidemic in America, industry supporters counter that there is little scientific evidence to prove this.
The popularity of the documentary Super Size Me, which is now in theaters, has raised the debate to deafening levels. In it, filmmaker Morgan Spurlock ate nothing but Big Macs and other McDonald's fare for 30 days and claimed it left him more than 20 pounds heavier and a physical wreck. Fast food industry spokespeople charge that the experiment was far from scientific, and they say they are offering a wider variety of healthy food options than ever before.
In a prior study, published early last year, Ebbeling and colleagues first reported kids who eat fast food tend to take in more total calories in a day than those who do not. Their research showed that on any given day, a third of the children in the U.S. eat fast food, and that the additional calories could account for an extra 6 pounds of weight gain per year.
Their new research consisted of two studies designed to assess the impact of fast food consumption on total calorie intake among both overweight and lean teenagers. In the first study 26 overweight teens and 27 normal-weight teens were taken to a food court and served a super-sized McDonald's meal, consisting of nine chicken nuggets, extra-large fries, a 20-ounce cola, and two individual bags of cookies. The meal lasted for an hour, and the teens could ask for extra portions if they wanted them.
Researchers found that both groups overate during the meal, taking in an average of 1,652 calories, or 61% of their total daily calorie requirements just from this one meal. The overweight teens ate approximately 400 more calories than the lean teens did.
In the second study, overweight and normal-weight teens were followed for four days. During two of those days the teens ate one meal at the fast food restaurant of their choice. Daily telephone interviews were conducted to determine calorie intake and physical activity.
While the lean teens in this study took in roughly the same amount of calories on the fast food and non-fast food days, the overweight teenagers consumed an average of an extra 400 calories on the days when they ate fast food. This indicates that the overweight teens were less likely to compensate for the calories they ate from fast foods.
Ebbeling says there are several characteristics of a typical "burger and fries" fast food meal set people up to overeat.
"This food is incredibly calorie dense -- there are a lot of calories per bite of food," she says. "It also tends to have a lot of fat, salt, and sugar, which are the tastes people like most, and it is served in enormous portions."
Nutritionist and author Marion Nestle, PhD, tells WebMD that the fast food industry is beginning to get the message that people will chose healthier foods if offered. McDonald's recently introduced salads, and announced that fries and colas would no longer be super-sized.
"It is not as if fast food company executives are sitting around tables saying, 'How can we make teenagers fat'," she says. "They discovered a long time ago that if they made things sweeter, fattier, and saltier, and made the portions huge, people would buy more of them."
While the increasing variety of foods offered is encouraging, Nestle says portion size is still a big problem in the restaurant industry in general.