Abstract： Objective To explore the effect of low calorie metabolism on the survival of HeLa cells exposed to X-rays,and the influence of starvation on the antioxidative factors in the blood of rats after irradiation.Methods MTT method was used to evaluate the impact of different concentration glucose on the proliferation of HeLa cells.Colony formation assay was employed to detect the influence of glucose ( 1,5,10 and 25 mmol/L) on radiosensitivity of HeLa cells. Flow cytometry assay was used to analyze distribution of cell cycle and apoptosis.60 male SD rats were randomly divided into 6 groups with 10 rats each.Rats in every two groups were fed ad libitum,fasted for 24 h and fasted for 48 h,respectively.Rats in one group of each approach were respectively exposed to whole-body X-rays at 11 Gy. At 2 h after irradiation,all of rats were sacrificed and their venous blood was collected.Elisa kits were used to detect superoxide dismutase (SOD) and total antioxidant capacity (T-AOC).Results An increased viability was observed in HeLa cells treated with the glucose at low concentration ( ＜25 mmol/L),while HeLa cell growth was inhibited by glucose at doses of ＞25 mmol/L. Relevant to cells treated with 1 mmoL/L glucose,SERs (sensitive enhancement ratio) in cells exposed to 5,10 and 25 mmol/L glucose were 1.07,1.10 and 1.23,respectively. A reduction of G2/M and S arrests and apeptosis caused by 6 Gy X-ray irradiation were observed [(49.68 ±1.88)％ and (35.54±1.45)％ at G2/M phase,(16.88 ±1.22)％ and (10.23 ±1.65)％ atS phase,t=10.42,5.61,P＜0.05]and in the cells treated with 1 mmol/L glucose compared with cells treated with 25 mmol/L glucose [ ( 25.50 ± 0.95 ) ％ and (7.56 ± 1.07 ) ％,t =21.72,P ＜0.05 ].Without irradiation,calorie restriction exhibited a negligible influence on SOD and T-AOC in rats.However,after 11 Gy irradiation,compared with rats fed ad libitum,the levels of SOD and T-AOC were significantly increased in rats with calorie restriction ( t =40.32,42.78, P ＜ 0.05 ).Conclusions Calorie restriction has a certain radioprotective effect in vivo and in vitro.