Abstract: Objective To investigate the changes of trunk fat and its relationship with bone mineral density in rats re-fed after calorie restriction and its possible mechanism. 
Methods Male SD rats, aged 8 weeks, were divided into normal chow(containing 4-week and 12-week subgroups, NC4 and NC12) group, calorie restriction for 4 weeks(R4) group, refeeding with normal chow after calorie restriction(RN) group, refeeding with high-fat diet after calorie restriction(RH) group. Trunk fat content and the whole body BMD were detected at the end of 4 and 12 weeks, along with body weight, fasting insulin(FINS), free fatty acids(FFA), inflammatory factors and bone turnover markers. 
Results (1) Refeeding after calorie restriction increased the trunk fat content and trunk fat ratio significantly(vs.NC12, P＜0.01).The bone mineral density decreased in R4 group(vs.NC4, P＜0.05). After refeeding, the recovery degree of bone mineral density in RN group was higher than that in RH group.(2) The levels of triglyceride(TG), inflammatory factors(tumor necrosisfactor-α and interleuken-6,TNF-α and IL-6), bone turnover markers(alkaline phosphatase, osteocalcin) were significantly decreased in R4 group(P＜0.05). After refeeding, the levels of serum alkaline phosphatase and osteocalcin in RH and RN groups increased, but were still lower than those in NC12 group(P＜0.05),while the levels of FINS, FFA, TG, TNF-α and IL-6 were significantly increased(vs.NC12, P＜0.05), especially in RH group.(3) In the linear regression analysis, trunk fat content and trunk fat ratio were both entered as predictors(r2=0.823， P＜0.001). 
Conclusion Refeeding after calorie restriction can lead to trunk fat accumulation and the whole body bone mineral density decrease, especially refeeding with high-fat diet. Lipid spillover and secretion of inflammatory factors increase due to fat accumulation in the trunk, and then affect bone turnover, which may be an important reason for reducing the whole body bone mineral density. 

Key words: bone density, fats；rats