Overweight Kids Find it Difficult Staying on a Low-Carb Diet

Not much is known about how low-carb diets work for kids, including whether they are safe and nutritionally sound, since they tend to be relatively high in fat.

For the new study, researchers randomly assigned 100 obese 7- to 12-year-olds to one of several three-month diet interventions: a portion-control diet, a low-carb diet, or a reduced glycemic load diet. Everyone also received weekly dietary counseling and biweekly group exercise

At 12 months, all three plans had worked equally well in controlling weight gain. The difference, researchers found, was that the low-carb plan was tough to stick with.

Dr. Shelley Kirk, of the Heart Institute at Cincinnati Children's Hospital Medical Center and lead researcher said, "All of these plans can work." "But the low-carbohydrate one was really challenging for kids to follow." The diet still helped control kids' weight, she said, because they followed it to an extent -- reducing carbs and calories, but not to the strict limits of the low-carb plan. All of that, Dr. Kirk said, suggests that a modified version of low-carb could work well for at least some kids.

And the diet based on reduced glycemic load was essentially that: certain carbs were unrestricted -- including fruit, vegetables low in starch, and 100% whole grains. More limits were placed on starchy carbs, but they were still allowed.

Over one year, children in all three diet groups had similar improvements in their body mass index (BMI), after accounting for the fact that they were still growing. Also, as reported March 1 in the Journal of Pediatrics, kids in all three diet groups ended up with healthier cholesterol levels. The low-carb group had a dip in triglycerides. And kids who focused on portion control or cutting glycemic load had signs of better blood sugar control. The bottom line, according to Dr. Kirk, is that there are options.

Dr. Kirk said that, for instance, kids could start by trimming carbs to jump-start their weight loss then switch to portion control for the longer haul -- which means more freedom in the foods kids eat. In the end, it comes down to negative calorie balance. So kids need not only a healthy eating plan, but daily exercise too,

The children in this study were part of a hospital-based weight loss program. And it's not clear if their results would translate widely into the real world.

"One of the hardest things is that families need to change," Dr. Kirk said. "So (they need to) think about the eating plan that the entire family can follow and stick with."

J Pediatr March 2012