Liquid and solid carbohydrate foods: comparative effects on glycemic and insulin responses, and satiety

It is speculated that the physical form (liquid or solid) of the food substrate has an independent effect on the body's satiety mechanisms. Using a balanced and controlled design, the objective of the present study was to determine the glycemic response (GR), insulin response (IR) and subjective feelings of satiety to two solid (rice [BR] and spaghetti) and two liquid (orange juice and a sugar-sweetened fruit drink [SSD]) foods. Ten healthy participants consumed volume (576 ml) and carbohydrate (50 g) matched portions of the above test foods following a 12-h fast. Blood samples were obtained for the ensuing 120 min for glucose and insulin determination. The subjects also completed visual analog scales (VAS) providing data on subjective feelings of hunger, fullness and satiety. Although there were some significant differences in the total incremental areas under the curve for the GR and IR to liquids and solids, there were notable distinctions in the pattern of the response curves. The BR and SSD elicited significantly different levels of subjective hunger, fullness and satiety. The VAS ratings for all four treatments were at or below baseline by 30 min post-consumption. There were no associations between the GR/IR and VAS ratings. Although the GR and IR were not different between liquids and solids, their differential response patterns could have an impact on satiety and merits further investigation.