A study by a University at Buffalo pediatric researcher investigating the causes of weight gain in children after they have their tonsils and adenoids removed to treat sleep-disordered breathing has shown that removing these tissues results in less fidgeting and other non-exercise motor activity.

This reduction in motor activity left an excess of calories, findings showed, resulting in an average 13 percent increase in excess weight based on participants' age, sex and height.

Results of the study appear in the February 2006 issue of the journal Pediatrics.

"To our knowledge, the current study is the first to demonstrate a significant reduction in sleep, waking and total daily motor activity in children with obstructed sleep-disordered breathing after removing the tonsils and adenoids, and the association of reductions in total daily motor activity with increases in the percent overweight in children, said James N. Roemmich, M.D., first author on the study.

Roemmich is an assistant professor in the Department of Pediatrics, UB School of Medicine and Biomedical Sciences and in the Department of Exercise and Nutrition Sciences, UB School of Public Health and Health Professions.

All children in the study underwent the surgery because they had enlarged adenoids, which can cause obstructive sleep-disordered breathing (OSDB).

In these young participants, weight gain as a result of removing the adenoids and tonsils to relieve breathing problems could create a vicious cycle.

"Weight gain in these children is a concern," said Roemmich. "Obesity may be a primary cause of OSDB, so additional weight gain may lead to a reoccurrence of obstructed breathing during sleep in spite of the surgery."

The study involved 54 children between the ages of 6 and 12 who were admitted to the University of Virginia's General Clinical Research Center, with which Roemmich was affiliated at the time.

The participants were assessed before surgery and at an average of 12.6 months post-surgery. Height, weight, body-mass index and percent overweight were determined.

During an overnight stay at the clinic, a number of measurements were taken to determine each child's behavior during sleep. Parents completed questionnaires on their child's snoring frequency and the amount of hyperactivity.

A subset of children wore a small motion monitor to log total amount of activity on their wrists for seven days and nights.

Roemmich said there may be several reasons for the children's reduction in energy expenditure and their subsequent weight gain.

"OSDB causes children to awake many times throughout the night, resulting in poor sleep quality," said Roemmich. "There is evidence that inadequate or poor sleep is related to hyperactivity in youth. Perhaps sleepy kids are more agitated and have a difficult time attending to tasks. Improved sleep may reduce hyperactivity, which in turn would result in less energy expenditure during the day.

"In addition, sleep energy expenditure in children with obstructed breathing has been reported to decrease by 5 calories per kilogram of body weight after tonsils and adenoids are removed as a result of the decreased work of breathing," said Roemmich. "So the reduction in fidgeting over the entire 24-hours could shift energy balance enough to cause excessive weight gain."

Further studies on activity and weight changes after removal of the tonsils and adenoids may provide a basis for developing diets and exercise plans for these children, he said.

Additional contributors to the study were Jacob E. Barkley, UB doctoral student in exercise and nutrition sciences; Lynn D'Andrea, M.D., Margarita Nikova, M.D., Alan D. Rogol, M.D., and Paul M. Suratt, M.D., from the University of Virginia School of Medicine, and Mary A. Carskadon, Ph.D., from Brown Medical School, Brown University.