Effects of food deprivation on intake of solid and liquid sugars in the rat

In free-feeding rats, glucose at 0.025 M or 2 M evokes a vigorous bout of drinking. Powdered sucrose evokes more feeding than would occur without it, but powdered glucose does not. Food deprivation has little effect on intake of 2 M glucose, but it markedly augments intake of the powders, which rises to caloric-intake values higher than that of the 2 M solution. This occurs even if the powders are offered only after solution intake has come to an end and at a time when it would remain inhibited. We conclude: 1. Some sweet-tasting commodities will evoke ingestive behavior in free-feeding rats, but others, some of them even sweeter, will not. 2. Solid carbohydrates follow different laws from concentrated carbohydrate solutions, in that the former, but not the latter, rise with deprivation. Intake of powders must therefore be limited or satiated by different and more permissive mechanisms from the ones that limit solution intake.