One of the main issues with respect to the usefulness of fat-replacers is their effectiveness. The question is whether or not people compensate for the "missing" energy due the replacement of fat by the fat-substitute. The present paper is concerned with the results of a number of studies carried out on the effects of the fat-replacer sucrose-polyester on food intake. Sucrose-polyester (SPE) is a substance with similar sensory and physical-chemical properties as fat, but it contains no metabolizable energy, because it is not digested in the human gastrointestinal tract. In the first two short-term studies, we replaced the fat by SPE in croissants. Thirty-three subjects in the first study and 34 subjects in the second study consumed 2 1/2 croissants, either with fat or SPE. After ingestion they rated subjective feeling of hunger, and recorded their ad libitum food intake. The results of both studies showed that the croissants with SPE had a similar satiating effect as the croissants with fat. In two subsequent short-term studies, we added either fat, SPE or water to warm meals served as lunch. The high water and high SPE lunches contained about 450 kcal, whereas the high fat lunches contained about 900 kcal. After ingestion of the lunches, subjects (39 in study 3; 35 in study 4) recorded their feelings of hunger. Two hours after the lunches, subjects were presented with an attractive buffet from which they could eat ad libitum. The results showed that hunger and food intake were similar after the water, SPE and fat lunches. The subjects did not detect the 450 kcal energy difference in the lunches. The last two studies with SPE lasted for 12 days. The results of these two longer-term studies were similar to the results of the short-term studies. There was little energy compensation and no fat compensation. It is concluded that fat replacers can be helpful in reducing fat and energy intake.