Abstract: Objective To explore the effects of low calcium diet after weaning on obesity in rats induced by high fat diet.Methods After weaning,male Wistar rats were randomly divided into two groups according to their body weights.One group was fed with a basic diet,the other was fed with a low calcium diet for 3 weeks.Then they were fed with basic diet for another 3 weeks.At the 6^th month,the rats of each group were further randomly divided into 2 groups.One group was fed with a high fat diet;the other was fed with a basic diet.The status of obesity of the rats was observed.Results Compared with rats with basic fed diet,the body fat content of rats with low calcium diet after weaning significantly increased and the level of serum lipids,the level of leptin also increased significantly(P<0.05),the level of HDL(high density lipoprotein),FT3(free triiodothyronine)decreased(P<0.05).Conclusion The tendency of obesity in rats with low calcium diet after weaning were more obvious than rats with normal diet after being fed a high fat diet.