This study was conducted to investigate the effect of an uncooked powdered food(UPF) on the weight loss and changes of the biochemical nutritional status for 20 overweight and 26 obese women in Iksan area. We just replaced common breakfast and dinner of the subjects with UPF. Their dietary intake status was evaluated by 24-hour recall method. Also anthropometric and biochemical measurements before and after the UPF program were estimated. The intake of energy, lipid and protein decreased and the quality of meals improved as people started to take UPF. Due to the energy loss by taking UPF, weight and body fat decreased significantly. The percentage of the body fat was high among the weight lost, from which we judged that the process of losing weight was successful. It is hard to predict whether weight loss will occur to people who are already in shape or not, but if overweight and obesity people regularly take UPF instead of other food products, we assume that UPF will help lessening the body fat. The most positive change among biochemical changes by taking UPF was the decrease of serum lipid contents. When overweight and obesity women replaced two out of three meals with UPF for 3 month period, no significant nutritional problems occurred. It seems that the 12weeks of UPF program used in this study was effective in improving anthropometric indices without producing the deficiency of iron or other susceptible nutrients.