Discussions are given about problems of human life at the initial stage of a CELSS, which consists of humans and plants in artificial environment controlled by various material circulation processes. The initial CELSS has many restrictions: for example, vegetable-base diet, no detergent, no dentifrice and no cosmetics. Such environmental changes produce new lifestyle and give stress to humans. The reduction of stress should be considered to be necessary conditions in the operation of closed ecological systems on the same level as the environmental condition and material process. The diet is an important part of the lifestyle. Problems and proposals of lifestyle in CEEF are discussed.