Children with obstructive sleep apnea (OSA) can have reduced growth rates. The primary treatment of OSA in children is removing the tonsils adenoids, referred to as an adenotonsillectomy. After this procedure, studies have shown an increase in weight. However, some kids that are overweight before adenotonsillectomy put on even more weight after the surgery.
This study looked at two groups of children, ages 5-10 years old, who had OSA. One group got adenotonsillectomy and the other group received no treatment - just watchful waiting. Sleep studies and height / weight measurements were repeated 7 months later. Results showed that body weight and body mass index (BMI) increased in both groups of patients. This may be because the sleep apnea severity improved in both groups. It's unclear why that happened, especially with the weight gain. I would think that would make the sleep apnea severity worse in the untreated group.
What was remarkable about the study, however, was that after adjusting for baseline weight and other variables, the weight gain experienced by those that had the adenotonsillectomy was significantly greater than the group that received no treatment. In those children who were already overweight at the start of the study, 52% became obese after adenotonsillectomy vs 21% in the group that did not receive treatment. The researchers proposed several mechanisms for weight gain after adenotonsillectomy: increased calories consumed, unhealthy food choices, decreased energy burned due to reduced work of breathing, improvement in blood oxygen levels, and increased growth hormone secretion.
The authors recommend monitoring weight, nutritional counseling, and encouragement of physical activity after adenotonsillectomy for OSA in children.