Bone Abstracts

The connection between osteoporosis and obesity is becoming a topic of increasing research. The adipocyte-secreted hormones, leptin and adiponectin, may be the mediators between adipose tissue and bone. The aim was to examine the changes in leptin and adiponectin with the weight and body composition (fat and lean mass) change during the 6-months weight loss program. Additionally, the relationship between two adipokines and BMD of various skeletal sites was also examined. Participants were healthy Caucasian women, n=100 (BMI range 25.0–40.0 kg/m², age 55.7±4.4 years, mean±S.D., at baseline), instructed to reduce energy intake. BMD and body composition were assessed by iDXA. Serum leptin, adiponectin and bone markers (osteocalcin, serum NTx and urine CTx) were analyzed with immunoassay kits. Pearson’s and partial correlation, and repeated measures ANOVA were calculated using SPSS. After 6-months, participants lost ~5 and~ 2% of body weight and fat, respectively, as well as some of the bone mass in several skeletal sites (although NS). As expected, serum leptin significantly decreased while adiponectin increased with weight and fat loss. Yet, leptin was still significantly positively correlated with total femur BMD (the same noticed at baseline) before and after controlling for age, years since menopause, physical activity, and dietary calcium and vitamin D intake. Adiponectin was significantly negatively correlated only with serum NTx before and after controlling for the above confounders. In conclusion, 6-month weight loss resulted in slight bone loss and decreased leptin and increased adiponectin levels. The positive effect of leptin on femoral BMD remained even after its decreased levels caused by weight loss.