It is obvious that suppressing intake energy is effective means for prevention of various lifestyle-related diseases, but it is not as difficult as resisting excessive appetite. It is pointed out that overeating is not only a cause of lifestyle-related diseases, but cause also possibilities of increasing the onset of cancer and shortening the life span. Many epidemiological studies have reported the possibility of a decrease in energy intake due to daily consumption of dietary fiber may be effective in preventing obesity. It is often understood that energy density is reduced by simply replacing low energy dietary fiber with high energy food ingredients, since some changes in energy density can be reimbursed by food consumption, there are also many negative opinions on whether dilution of energy density by dietary fiber is involved in anti-obesity. A large numbers of papers have reported that dietary fiber, especially that with high viscosity and water-soluble is used to alleviate hunger during treatment of obesity due to limited intake energy. However, if the reduction in intake energy shown in the epidemiological survey is essential, dietary fiber should suppress spontaneous energy intake, and the relevance to these results is less. We believe that it is necessary to examine whether dietary fiber manifests the obesity prevention effect by suppressing spontaneous eating behavior, and if has such effect, it is necessary to verify what kind of mechanism occurred. The energy in the meal ingested by the living body is sensed by gastrointestinal tract or adipose tissues. In the gastrointestinal tract, it receives physical stimulation by a simple bulk effect and chemical stimulation of nutrient components, and issues a signal that responds to excess or deficiency of energy. The absorbed nutrient components stimulate the liver and pancreas, which are quickly secreted to the stimulus, are sensitively sensed by the vagus nerve and are transmitted to the appetite regulation mechanism of the central system, and dramatically change the eating behavior, is considered to have no significant impact on long-term energy balance. On the other hand, unlike other tissues, the fat accumulation degree is sensed in fat tissue, and according to long-term observation strong appetite-suppressing hormone leptin is secreted. It is well known that secretion of leptin itself or a deficiency on sensitivity of animal causes an extreme obesity, has become clear that it has the most important function in the long - term regulation of energy homeostasis, and has attracted attention in recent years. Much attention was paid to how the signals control eating behavior but there are still a lot of unexplained parts yet. In the hypothalamus, such short-term response and long-term energy satisfaction situation like leptin are also taken into account, a neurotransmitter expressing stimulation or suppression of appetite is expressed, and energy intake is controlled by gaps in these signals, it is considered to maintain energy homeostasis.