'We do know that even a modest reduction in BMI in the order of 5 percent or so does translate to significant health benefits but we don't know ... if those health benefits endure over time.'

The findings appear in the June 15 issue of the Journal of the American Medical Association.

"The good news is that it's out there, and has some efficacy," said Dr. Robert Kramer, medical director of the Better Eating and Activity for Children's Health Clinic at the University of Miami School of Medicine. "But it highlights the difficulty of just treating obesity in general because the benefit, although statistically significant, is modest at best." Kramer was not involved with the study.

Public Health Crisis

Even with this modest benefit, the "fat pill" is not a solution unto itself.

Participants in this study also exercised, adhered to a weight-loss diet and received behavioral therapy -- all of which experts agreed are crucial components of any weight-loss plan.

"We don't want to have kids crossing the doctor's door, and being given a prescription and told to go home," said study author Dr. Jean-Pierre Chanoine, a clinical professor and head of the division of endocrinology and diabetes at British Columbia Children's Hospital in Vancouver. "This is not the goal. This has to be combined with diet and lifestyle."

Overweight and obesity among children and adolescents is quickly becoming a public health crisis, and one for which there is no effective solution. In certain ethnic minorities in the United States, the study authors pointed out, 23.4 percent of adolescents are now obese. Overweight children have a 15-fold greater risk of becoming overweight adults and, according to the study, are a "notoriously difficult-to-treat population."

Orlistat, which was first approved for use in adults, works by decreasing absorption of fat in the intestine by up to 30 percent.

Decrease in BMI

The current study involved 539 obese adolescents aged 12 to 16, 357 of whom received 120 milligrams of orlistat three times a day while another 182 received a placebo. Both groups were given instructions on diet, exercise and behavior modification. The one-year trial was funded by the drug's maker, Hoffman-La Roche.

Individuals in both groups experienced a decline in body-mass index (BMI) for the first 12 weeks. After that point, individuals on orlistat continued to go down while those in the placebo group increased and eventually topped their baseline BMI.

More than a quarter (26.5 percent) of those taking orlistat had a 5 percent or more decrease in BMI, compared with 15.7 percent of the placebo group. Weight, however, had increased: 0.53 kilograms (over 1 pound) in the orlistat group and 3.14 kilograms (about 7 pounds) in the placebo group. The difference was apparently due to changes in fat mass.

Adolescents taking orlistat had higher levels of mild to moderate gastrointestinal side effects such as nausea, greasy stools, abdominal pain and gas.

"Because of its side effects, it's not the number one diet pill," said Dr. Robert Yanagisawa, program director of the Mount Sinai Weight Management Program in New York City. "People tend to go more for something that cuts appetite."

Long-Term Benefits?

The study showed no differences in response to the drug between girls and boys and between ethnic groups (although the study group was primarily white and female). Participants who responded in the first few months were more likely to have a net benefit by the end of the study.

"If you lose a lot of weight in the first three months of treatment, this is associated with a better response at the end," Chanoine said. "If it doesn't work after three months, it's unlikely to bring a benefit."

It's not clear how long any individual will have to take the drug for sustained benefits, or how long it would be safe to take the medication.

"The biggest question, assuming they stop these patients at 52 weeks, is what is going to happen long-term to the treatment group versus the placebo group. Will they eventually even out, which would be my suspicion," Kramer said. "This is the dilemma we face: Should we consider that someone who is obese needs chronic, long-term therapy and, if so, is that safe to do, especially in the pediatric population?"

"If we are going to use it for a defined period of time, is it going to offer long-term benefits?" he continued. "We do know that even a modest reduction in BMI in the order of 5 percent or so does translate to significant health benefits but we don't know, again, if those health benefits endure over time."

More information: The American Obesity Association has more on childhood obesity.