We investigated the effects of cellulose supplementation on fecal consistency and fecal weight. About 26 women were classified into two groups–normal defecation and constipation groups. All subjects ate the following meals during the experiment: ordinary meals (first week), experimental meals (second week), and experimental meals mixed with 4 g (third week) and 8 g (fourth week) cellulose. The experimental meal contained 16.7 g fiber. Fecal weights, fecal water content, fecal consistency, and defecation frequency were measured during the experimental period. As a result, in the normal defecation group, the mean fecal weight was 222.9 g day−1 in the first week, and thereafter decreased. Although 20/24 g of fiber intake in the third/ fourth week increased the fecal weight to over 150 g, the fecal consistency was still lower than the optimal consistency of around 300 g cm 2. However, these changes were not observed in the constipated group.