Japan is moving toward an advanced-age society at a very high speed. In 2003, mean life expectancy of the Japanese was 78.36 years for males and 85.33 years for females. The leading causes of death in Japan are malignant neoplasm, heart disease, and cerebrovascular disease, followed by suicide and accidents for the middle-aged but followed by malnutrition-related infectious diseases for older persons. Few studies have examined the beneficial effects of long-term, light exercise throughout life, which is almost equivalent to regular physical activity in day-to-day life in humans, on age-related changes in physiological and metabolic functions. Compared with sedentary daily living, long-term, light exercise further enhanced the benefits of restricted feeding on age-related deterioration of physiological and metabolic variables and improved body composition but did not prolong survival at 900 days of age. Soy protein appears to be a useful vegetable protein for preventing age-related diseases, compared with other proteins.