Some investigations report that conjugated linoleic acid (CLA) and phytosterols could modulate body composition, in spite of some contradictory findings. We investigated the effect of dietary CLA and/or phytosterols supplementation on energy intake, body weight gain and corporal composition in two different experimental models. Swiss male mice and Sprague-Dawley male rats were fed with high-fat diet (35%) or normal-fat diet (9%), as for supplements, 2% of the mixture CLA isomers c-9, t-11CLA : t-10, c-12CLA and 2% phytosterols. Animals were divided into five groups (n=8) each: standard group (ST), high-fat group (HF), and three high-fat groups fed with diets supplemented with CLA (CL), phytosterols (PH) and CLA plus phytosterols (C+P). Analyses of moisture, total protein and ash were performed according to methods described by Association of Official Analytical Chemists. Total lipids were determined by Bligh & Dyer method. Variance and Tukey's tests (p <0.05) was used. Swiss mice supplemented with CLA and CLA+phytosterols showed the most efficient weight loss, as well as increased protein and decreased lipid of the carcass, when compared with the high-fat group. However, in rats these effects were related to phytosterols. There was no significant difference among the experimental high fat groups for ash content for obese rats, although this content showed an increase in the CLA group for mice. Mice and rats showed significant differences in the supplements metabolism. These results point out the need for further investigations regarding the mechanisms of action of phytosterols, as well as the CLA, in different experimental animals.