Food intake (FI) can be predicted on the basis of variables that describe food quality and the animal. Live weight (LW) is usually the only variable that is used to describe the animal. Animal fatness, as estimated by condition score (CS), can affect FI at a given LW. Body lipid produces signals (leptin) that affect energy intake and energy expenditure. If fatness acts on intake via its effect on energy expenditure, the effects of body lipid content on food intake can be incorporated into an existing intake model. Our objectives were to construct and test models that predict effects of fatness on intake and performance, using data obtained with ewe lambs to parameterise and test the models.