Objective. To evaluate the effects of endosperm of tara seeds (ETS) and powder of Agave americana leaves (AAL) on body weight and intestinal transit time in Holtzman rats. Materials and Methods. Twenty-five male Holtzman rats, individually caged, and distributed into five groups were fed for 21 days with one of the following treatments: T1, diet with 6% alpha cellulose (Control); T2, diet with 6% ETS; T3, diet with 6% AAL; T4, diet with 10% ETS; and T5, Diet with 10% AAL. Feed intake, body weight gain, apparent digestibility of fat, characteristics of feces (fat content, weight, moisture, volume, and pH) and intestinal transit time were recorded. One-way analyses of variance (ANOVA) were performed, as well as Tukey’s multiple means comparison. Results. Diets with 6% and 10% of ETS resulted in a reduction of feed intake, apparent digestibility of fat, and fecal pH, and said results had an effect in the reduction of body weight gain of 37.0% (p=0.008) and 50.9% (0.001), compared with the control diet. The diet with 10% of AAL powder reduced the intestinal transit time from 642 min (control) to 532 min (p=0.242). Conclusions. Diets containing EST regulated body weight gain, while the diet with AAL powder had no effects on the intestinal transit time in rats. © 2018, Instituto Nacional de Salud. All rights reserved.