Obesity often follows the young into adulthood
Some adolescent memories — prom dates, fashion choices, Facebook postings — tend to fade and, mercifully, disappear in the transition to adulthood. But a study released Tuesday finds that one increasingly common source of teen angst — obesity — has a cruel knack for following adolescents into their adult years, then tightening its grip.
The result not only confers profound health risks for teens whose excess weight follows them and accelerates into adulthood, it also spells a looming public health disaster in a country where almost 1 in 5 adolescents is obese, experts say.
By the time they reach their late 20s to early 30s, people who were obese between 12 and 21 are more than seven times more likely than normal-weight or overweight peers to develop severe obesity — defined as having a body mass index, or BMI, of 40 or more — according to the study published in the Journal of the American Medical Assn.
For women and for ethnic minorities, the likelihood of proceeding from adolescent obesity to adult severe obesity is particularly pronounced. Among women, 51.3% of those who had been obese when they were younger became severely obese adults (for men, the figure was 37.1%). Among African American women, 52.4% who had been obese in earlier years went on to become severely obese.
By comparison, 7.9% of all participants in the study, and less than 5% of those whose weight was in the normal range, became severely obese in adulthood.
The authors, epidemiologists based in North Carolina, estimated from their findings that 1 million Americans who were between the ages of 12 and 21 in 1996, when the study began, became severely obese adults. As they did so, they took on the increased risk of developing obesity-related conditions such as cardiovascular disease, Type 2 diabetes, certain cancers and musculoskeletal pain.
The report comes against the backdrop of evidence that the ranks of the severely obese — typically, those who carry at least 80 to 100 pounds of excess body weight — are rising faster in the U.S. population than those classified as moderately obese. Given the scarcity of solutions — drugs and diet-and-exercise interventions have proved less safe and effective than experts had hoped — the authors note that “prevention is critical.”
For those already obese, the authors said, it is important to identify those at greatest risk of becoming severely obese and focusing weight-loss programs on them.
The investigation tracked 8,834 participants ages 12-21 at the study’s start for 13 years. Because of the long follow-up, the study provides a clearer picture than most of obesity’s progression in individuals of different genders, ages and ethnicities, said lead author Penny Gordon-Larsen, an epidemiologist with the Carolina Population Center at the University of North Carolina.
In particular, the findings underline that for children who struggle with their weight, the transition to adulthood can be a particularly perilous crossing, Gordon-Larsen said.
Obese teens increasingly are steered toward riskier measures to avert future health problems, including bariatric surgery — a weight-loss intervention that grew sevenfold among teens between 2005 and 2007, according to a recent report. The authors of the JAMA study suggested such surgery may be justified because it “is the only treatment to have long-term success,” albeit with “major potential complications.”
Pediatric endocrinologist David S. Ludwig, director of Children’s Hospital Boston’s Optimal Weight for Life program, said the JAMA study emphasized the “critical importance” of treating childhood obesity early, before poor lifestyle habits can become deeply ingrained. Early obesity also “may produce changes in metabolism, hormones or the brain that oppose weight loss,” Ludwig added.
At the same time, some experts in weight management across the lifespan said the study’s usefulness was limited by its reliance on the BMI as the primary measure of an individual’s healthful weight.
“I’m not a big fan of BMI, especially for kids,” said Dr. David Heber, director of UCLA’s Risk Factor Obesity Program. A rough measure of fat based on an individual’s height and weight, the BMI can be useful for detecting population trends, but is often not the best measure of an individual adolescent’s fitness or prospects of developing obesity-related health conditions, he said.
Instead, Heber prefers to measure an adolescent’s fat and lean-muscle mass and calculate their relative proportions. “They’ll tell you what your target weight should be,” he said.