Short-term effects of energy density on salivation, hunger and appetite in obese subjects

Obese patients were admitted to a metabolic unit for weight loss. On two paired-test days subjects were given disguised preloads of 100 kcal (0.42MJ) or 300 kcal (1.26MJ). When presented with a meal one hour after the preload, subjects salivated more and reported more hunger, but not appetite, after the low compared to the high preload. A different group of 14 subjects were given preloads of the same energy content (200 kcal, 0.84MJ) on paired-test days. On one day they took 1 g methyl cellulose with 100 ml water drink immediately before the preload. Neither the energy-dilution effect of the water, nor the effect of the methyl cellulose caused a significant decrease in salivation, hunger or appetite scores one hour after the preloads of equal energy content. These results show that salivation and hunger are inversely related to short-term changes in energy intake in obese subjects. Alterations in energy density without changing energy intake or the ingestion of methyl cellulose have no effect on salivation, hunger or appetite.