James Joyner · · 12 comments

A new CDC study suggests that Americans may have reached the limits of human obesity.

Americans, at least as a group, may have reached their peak of obesity, according to data the Centers for Disease Control and Prevention released Wednesday.

The numbers indicate that obesity rates have remained constant for at least five years among men and for closer to 10 years among women and children — long enough for experts to say the percentage of very overweight people has leveled off. But the percentages have topped out at very high numbers. Nearly 34 percent of adults are obese, more than double the percentage 30 years ago. The share of obese children tripled during that time, to 17 percent.

“Right now we’ve halted the progress of the obesity epidemic,” said Dr. William H. Dietz, director of the division of nutrition, physical activity and obesity at the disease control centers. “The data are really promising. “That said, I don’t think we have in place the kind of policy or environmental changes needed to reverse this epidemic just yet.”

Dr. Dietz said the data probably reflected increased awareness of the obesity problem, especially among women, “who buy food, prepare it and see it, and they’re making changes for themselves that they’re also making for their kids.” He also cited a reduction in “less healthful foods” at school.

Some experts, though, were not optimistic that the leveling off was a result of improved eating and exercise habits. “Until we see rates improving, not just staying the same, we can’t have any confidence that our lifestyle has improved,” said Dr. David Ludwig, director of the Optimal Weight for Life Program at Children’s Hospital Boston.

Dr. Ludwig said the plateau might just suggest that “we’ve reached a biological limit” to how obese people could get. When people eat more, he said, at first they gain weight; then a growing share of the calories go “into maintaining and moving around that excess tissue,” he continued, so that “a population doesn’t keep getting heavier and heavier indefinitely.” Furthermore, Dr. Ludwig said, “it could be that most of the people who are genetically susceptible, or susceptible for psychological or behavioral reasons, have already become obese.”