Sensory versus dietary factors in cafeteria-induced overweight

Normal Wistar rats became hyperphagic and obese when presented with high-fat, high-sugar or "cafeteria" diets. This phenomenon could be due to the very palatability of the offered foods but a metabolic factor could be suspected. In an attempt to distinguish the effects of the nutritional characteristics from those of the sensory properties of food, a new cafeteria diet, the "isocafeteria" diet, was developed. It consists of a choice of foods of similar, well-balanced composition but varying in taste, smell and texture. It was confirmed that in normal Wistar rats, the high-fat and the traditional "cafeteria" diet led to extra-weight gain. It was demonstrated that the daily presentation of a new choice of the palatable foods which composed the "isocafeteria diet" led also to a sustained increase in food intake and to overweight. Variety and high palatability are per se sufficient factors to overcome regulatory mechanisms. It was shown that the metabolic efficiency of such a regimen was strikingly higher than those of high-fat and traditional cafeteria diets.