L112 and FF45 are two polyglucosamines with similar characteristics and molecular weights. Three groups of 15 young male rats each were fed a standard diet or a diet containing 2% L112 or FF45 for 4 weeks, and we measured their body weight; water and food intake; triglyceride and total, low-density lypoproteins (LDL) and high-density lypoproteins (HDL) cholesterol levels; and the amount of feces and fecal water and lipid concentrations. The results showed that both L112 and FF45 reduced the increase in body weight in comparison with controls (respectively 152+/-18.7 g and 155+/-18.7 g vs 166+/-18.1 g; ANOVA P<0.05). Total food intake during the study period was significantly greater in the animals treated with L112 or FF45 (respectively 780+/-49.9 g and 787+/-61.7 g vs 742+/-53.0 g), with a significant loss of "food efficiency". Water intake was similar in all three groups. There was no significant change in plasma lipid profiles in any of the groups except for a significant decrease in HDL cholesterol in the animals treated with L112. Twenty-four-hour fecal weight was 7.8+/-1.70 g in the controls, 10.1+/-1.98 g in the rats treated with L112, and 9.0+/-1.21 g in those treated with FF45 (Dunnet's test vs controls: P<0.05). Fecal lipid and water concentrations were significantly higher in the polyglucosamine-treated groups (P<0.05 Dunnet's test).