Now it seems that the notion that fat substitutes will keep fat off our bodies is a big fat lie. That, at least, is the suggestion of a study by Purdue University researchers that found that when rats consumed a fat substitute, signals that could help control food intake were disrupted, and the rats gained weight. The study gave laboratory rats crushed potato chips as a supplement to their diet, and divided the rats into two groups that were given either a low-fat chow diet or a high-fat chow diet. Wait, it gets more complicated: These groups were each split into two smaller groups. One group on each diet was fed a mixture of high-fat chips and the fat-substitute chips, containing olestra, which is a synthetic fat with no calories, while the other group received only regular high-fat chips. After four weeks, rats on the high-fat chow diet gained more weight and developed more fatty tissue when they were given fat-substitute chips compared to the animals that ate only regular high-fat chips. The researchers also found that when the rats that had previously consumed both fat substitute and high-fat chips were moved from a low-fat standard chow diet to a high-fat chow diet, they gained more weight.