Most teen-agers overeat when they hit the fast food counter but lean youngsters stay that way by cutting back the rest of the day while their overweight peers do not, according to a study published Tuesday.
“We don’t know if this is an inherent problem that leads to obesity or develops as a consequence of obesity,” said David Ludwig of Children’s Hospital in Boston, an author of the study.
“It may be that years of overeating leads to a bit of a disconnect in the appetite mechanism,” he said in an interview. ”At the very least its either causing obesity or contributing to the maintenance of obesity.”
The study, published in this week’s Journal of the American Medical Association, was designed to find out why only some adolescents are obese although almost all eat fast food.
One part of the study involved 54 adolescents age 13 to 17 about evenly divided between overweight and lean who were given extra large fast food meals and told to eat as much as they wanted in one hour.
In a second part of the study researchers did a telephone survey of 51 members of the same group to find out how much they ate under unsupervised conditions over four days -- two when fast food was available and two days when it was not.
In the first part of the study, they all consumed calories equivalent to more than 61 percent of their estimated daily energy requirement and in general the overweight group ate more.
Little change in obesity
In the second part of the study, overweight teens consumed ”significantly more total energy” on days when fast food was available -- something not observed among the lean group.
“This observation suggests that overweight individuals do not compensate completely for the massive portion sizes characteristic of fast food today,” the study said. “These findings suggest that, at least, fast food consumption serves to maintain or exacerbate obesity in susceptible individuals.”
Ludwig said one factor is that highly processed and tasty fast food goes down more easily. Consuming the equivalent to a 1,600-calorie fast food meal in vegetables and whole grains requires chewing and time, and would leave the body feeling full long before reaching the same level.
In a second paper published in the same issue, the U.S. Centers for Disease Control and Prevention reported little change in the obesity epidemic in the United States, based on an update of information from a national probability sample.
“There is no indication that the prevalence of obesity among adults and overweight among children is decreasing,” it said. “The high levels of overweight among children and obesity among adults remain a major public health concern.”