Bone Abstracts

Objectives: Weight loss therapy is the principal non-pharmacological method for prevention and treatment of simple obesity in childhood. This intervention may influence bone metabolism in children, but this phenomenon is not well understood. The aim of this study was to assess the changes in body composition and in the profile of bone markers after weight loss in obese prepubertal children.

Methods: We determined serum BALP (bone alkaline phosphatase), CTX-I (C-terminal telopeptide of type I collagen) and OC (osteocalcin) by ELISA kits. Biochemical markers, body composition and bone mineral density (assessed by dual-energy x-ray absorptiometry) were studied in 30 obese children (z-score BMI >2) before and after 12 months of lifestyle intervention (low-energy diet, physical activity). The recommended daily energy intake was 1200–1400 kcal per day. The diet was composed of 20% protein, 30% fat and 50% carbohydrates. The control group consisted of 30 non-obese children (z-score BMI <−1+1>). This study was approved by the Ethics Committee of the Institute of Mother and Child.

Results: Obese children had higher BALP activity by about 20% (P<0.001) and similar values of CTX-I and OC compared with non-obese children. In patients after therapy, we observed decrease of BMI value by about 10% (P<0.001) and lower percent of body fat mass (41.0±5.0% vs 36.1±4.7%; P<0.001). After weight loss the BALP and OC values in obese patients were unchanged, whereas CTX-I concentration increased by about 10% (P<0.05). z-score total BMD and Z-score BMD L2–L4 in obese children before therapy were higher than in controls (P<0.001) and significantly decreased after therapy (p<0.01).

Conclusion: Our results suggest that obesity during the prepubertal period is associated with alterations in the profile of bone markers and greater whole-body bone mass as a result of increased bone formation rather than reduced bone resorption. The changes in bone metabolism after 12-month lifestyle intervention seem to be related to alterations in bone resorption process.

Disclosure: The authors declared no competing interests.