This study was conducted to investigate the effect of an energy restriction program on the weight loss and changes of the biochemical nutritional status for 35 obese women. The energy restriction program took place over a 3-week period that was devided into two parts. The first part consisted of 750-800kcal diet and the second part of 800-1000kcal. Subjects were provided a low energy formula and a menu for the recommended diet. Anthropometric and biochemical measurement before and after the energy restriction program were estimated. Mean weight loss was 3.0kg, accordingly the obestiy rate was lowered from 40.2 to 34.4, BMI from 29.2 to 28.9 and fat weight from 23.3kg to 21.0kg( <0.01. <0.05). Waist circumference loss was most prominent(4.4%) compared to triceps(21% loss)and hip circumference(2.2%loss). Mean RBC count, hemoglobin and hematocrit were significantly lowered( <0.01) but they were in the normal range. Systolic blood pressure was significantly decreased from 124.1mmHg to 113.1mmHg . Mean SGOT and SGPT were lowered from 29.3u/L to 20.0u/L and from 28.7u/L to 16.6u/L, respectively. It seems that the 3 weeks of energy restriction program used in this study was effective in improving anthropometric measurements without producing deficiency of iron or other susceptible nutrients.(Korean J community Nutrition 2(5) : 695-700,1997)