Effect of prefeeding lipid on food intake and satiety in man.

Experiments were carried out in normal volunteers to investigate whether preingestion of lipid reduces food intake. In the first set of experiments, 300 ml beef consomme soup with or without 60 g margarine was fed to each of six volunteers, followed 20 minutes later by either a low fat solid meal or a preselected appetising meal. Subjects were allowed to eat as much of the meal as they wished. Preingestion of the high fat soup had no significant effect on the consumption of either of the solid meals and did not influence sensations of hunger or fullness. As we have previously shown that prefeeding a fatty soup delays gastric emptying of a subsequent meal, this suggests that gastric distension may play a relatively minor role in regulating food intake. In the second set of experiments, we studied the effect of ingesting either a high fat breakfast (65 g fat, 927 kcal) or a similar low fat breakfast (8-1 g fat, 418 kcal) on the consumption of a preselected appetising lunch in six healthy volunteers. The high fat breakfast significantly reduced the amount of the meal eaten at lunchtime (p less than 0.02), the total energy intake from the meal (p less than 0.05) and the rate of eating (p less than 0.05) compared with the low fat breakfast. When the subjects were presented with their lunchtime meal they felt significantly less hungry after the high fat breakfast (p less than 0.05). Only a small proportion of either meal (15% of the high fat meal v 12% of the low fat meal) remained in the stomach and plasma glucose concentrations had returned to fasting levels. Plasma triglyceride concentrations were much higher at lunchtime after ingestion of the high fat breakfast (p<0.001). The energy intake from the breakfast and lunch combined was not significantly different on the high fat breakfast day, indicating that the energy consumption at lunch compensates for the amount eaten at breakfast. These results are compatible with the concept that the interaction of nutrients with small intestinal receptors may play a part in limiting food intake.