The effect of low-energy diet (Low protein or low fat-diet) was studied using male albino rats. The experiment was expended to 45 days (30 days treatment and 15 days recovery period). Body weight gain or loss as well as blood samples for blood picture (R.B.CS. W.B.CS count, Hb. concentration, Hct value and erythrocyte indices such as MCV, MCH and MCHC) well recorded Biochemical examination for glucose concentration, total protein, albumin, globulin and A/g ratio. Triglyceride level, total cholesterol and LDL-cholesterol, and HDL-cholesterol level, in addition to some hormones such as insulin, Testosterone and Leptin levels were examined at the end of the treatment period and the recovery period. A significant decrease in body weight gain percentage was observed in group fed low protein or Low fat-diet and the body weight improved during and after the recovery period. A significant decrease in R.B.CS, W.B.CS, count and Hb. concentration, and Hct value in treatment period and improved during and after recovery period. Total proteins, albumin and globulin were significantly affected by low protein or low-fat diet treatment in comparison with the control group. These effects were significantly counteracted by balanced diet. A significant decrease in triglyceride, total cholesterol, LDL-cholesterol and HDL-cholesterol were observed in groups received diet containing low-protein or low fat as compared with the control group. The results of the present study showed a significant reduction in (Leptin, insulin and testosterone) level after treatment for 30 days and recovery period for 15 days.