Consumption theory, so far, have not dealt with physical constraint in food consumption though consumptions of several foods shows its restriction in expanding the quantities to be consumed. For example, the consumption of rice in Korea has been decreased over decades, despite increase in income and rise in price. Such economic phenomenon has been explained just by the inferior- good features of rice. However, it can also be explained by the fact that individual consumers have reached the consumption of food. Under such constraint, individual consumers cannot help decreasing quantity of a food if she increases the quantity of the other food. This paper shows theoretically the effects of changes in price and income of individual foodconsumption under the physical constraint. If the physical constraint is applied, the consumption of a food is affected by the change in price of a substitute more when without the constraint, and there should exist at least one inferior good when consumption of one or more food are increased.