Rats on a macronutrient self-selection diet eat most meals from a single food cup

Computerized meal pattern analysis was performed on female Sprague-Dawley rats (n = 10). Rats were housed for 14 days in cages adapted for macronutrient selection. Rats selected their diet from vitamin and mineral supplemented, semipurified sources of carbohydrate, fat and protein, in three individual food cups. For analysis of meal patterns, minimum meal size was > 50 mg, and mean minimum intermeal interval was 7.9 min. Daily energy intake averaged 289.0 kJ, with 75% occurring during the dark cycle. Energy intake was 28% carbohydrate, 50% fat and 22% protein. Of 12.3 daily meals, 56% were from one, 35% from two, and only 9% of the meals were from three food cups. Seventy percent of the time carbohydrate was the first meal of the dark cycle. The average number of meals per day eaten from carbohydrate, fat, and protein were not significantly different (6.9, 6.2 and 5.6, respectively, p > 0.05). Energy intake for a meal was greatest when fat was eaten (18.35 kJ), than when either carbohydrate (8.68 kJ) or protein (8.97 kJ) was eaten. Meal duration was 7.03 min for carbohydrate, 3.75 min for fat, and 7.47 min for protein. These results provide evidence that rats on a macronutrient self-selection diet eat most meals from a single macronutrient source.