Diet self-selection and food hoarding after food deprivation by Siberian hamsters

Siberian hamsters (Phodopus sungorus) increase food hoarding, but not food intake, after a fast. Because the physiological mechanisms underlying these changes in food hoarding are virtually unknown, we sought insight into these mechanisms by allowing hamsters to self-select their diet from food sources varying in macronutrient composition and caloric density ("dietary wisdom"). Therefore, the effects of food deprivation length on diet self-selection were tested in adult female hamsters after adaptation to three composite diets: sunflower seeds (SS), pellet chow (PC), and rabbit chow (RC). One group initially was fasted for 32 h, the other for 56 h, and then each was refed. The remaining nonexperienced fast was instated after prefast body mass, food intake, and hoarding were recovered. Food hoarding, but not food intake, was increased regardless of fast length or sequence; moreover, the largest increase in food hoarding was on the first day of refeeding and was primarily reflected as increased SS hoarding. When the longer fast occurred first body mass loss was greater and the increased food hoard size was maintained for more days than when the longer fast came second. The order of food intake and hoarding preferences was not changed after a fast (SS > PC > RC), but the degree of food hoarding preference for SS was exaggerated. Collectively, these results support the notion that food hoarding increases with decreases in lipid stores, and show that when internal lipid stores are decreased, external lipid stores are preferentially increased.