Japan once was a country suffering from undernourishment due to the shortage of food supply during and right after World War. Within a half century, however, Japan became one of the most developed industrial counties and, during the process of the economic development, adopted Western life style and eating habit: the Japanese have, with sufficient food supply, the intake of far more animal protein and lipid today than before the War. It is true that the increased intake of animal food has contributed to the nutritional improvement and physical development of Japanese people; but its excessive intake has also led to obesity and life style-related diseases such as diabetes mellitus. Excess energy is deposited and saved as subcutaneous and visceral fat, and prepares the body for starvation; but fat deposit in the well-nourished body becomes prevalence of obesity. This is one serious problem which the world faces today. Another seriously nutritional problem is that more than 13% of the world population is suffering from under-nutrition. Under-nutrition beyond nutritional adaptation is a risk factor leading to death. We have to deal with two contrasting issues: the control of food intake which meets the needs of the body in developed countries and the challenges to malnutrition resulting from inadequate food supply in developing countries. Nutritional education in individual countries should be regarded as imperative. (Contains 5 tables and 23 footnotes.)