A commercial starch blocker was used to study the digestin of starch (potato) in mature female rates for four weeks. Two levels of starch blocker were used. The first level was calculated to inhibit starch digestion at 50%, the second was calculated to inhibit starch digestion at 100%. No significant effects on the body weights (271.10±29, 277.7±43, 259.1±25 g) were found among the groups of rats at 0%, 50% and 100% inhibition levels, respectively. Feed intakes were not affected. However, fecal copper and zinc excretions increased significantly (p<0.05) due to the inhibitors. Fecal copper excretions were 0.468±0.14, 0.578±0.09, 0.617±0.07 mg/rat/week, while fecal zinc values were 0.625±0.14, 0.859±0.32 and 0.778±0.26 mg/rat/week when no inhibitor was fed, at 50% inhibition and at 100% inhibition respectively. Thus, while use of starch blockers did not promote weight loss in the mature female rats, utilization of copper and zinc were negatively affected.