PROBLEM TO BE SOLVED: To provide an agent capable of safely oral ingestion, inhibiting reduction of lean body weight even with dietary restriction by oral ingestion and inhibiting rebound of weight after diet and efficient for increase of lean body weight.SOLUTION: There is provided an increasing agent of lean body weight, which is at least one kind selected form hardly digestible dietary fiber and polydextrose as a water soluble dietary fiber said to have increase of digestion absorption function, fermentation of dietary fiber, assimilation effects by intestinal bacterial flora, bulking effects, ion exchange reaction, water content adsorption effects, and absorption inhibition effects of saccharide, lipid or the like.SELECTED DRAWING: Figure 3
