There is evidence that food consistency may influence postprandial physiological responses. Recently we found that homogenization of a vegetable-rich meal significantly delayed the gastric emptying rate and was more satiating than the same meal in solid–liquid form. In this present study we investigated whether homogenization also influences endocrine and metabolic responses to the meal. Eight healthy men, aged 21–28 (mean 24·5) years, were given the meal (cooked vegetables 250 g, cheese 35 g, croutons 50 g and olive oil 25 g, with water 300 ml; total energy 2·6 MJ) in both solid–liquid (SM) and homogenized (HM) form, in random order, at 1-week intervals. Variables assayed were plasma glucose, insulin and glucose-dependent insulinotropic peptide (GIP) levels for 2 h and diet-induced thermogenesis (DIT) for 5 h. Plasma glucose pattern was similar after both meals. However, HM induced significantly greater insulin, GIP and DIT responses than SM. Mean integrated areas under the curves (AUC) were 1·7 (SEM 0·38) V. 1·2 (sem 0·33) U/l per 120 min (P = 0·005) for insulin, 19·9 (sem 2·44) v. 16 (sem 1·92) nmol/l per 120 min (P = 0·042) for GIP, and 237·7 (sem 16·32) v. 126·4 (sem 23·48) kJ/300 min (P = 0·0029) for DIT respectively. Differences between GIP-AUC after HM and SM correlated significantly with differences between insulin-AUC after HM and SM (r2 0·62, P = 0·021). These findings demonstrate that homogenization of a meal results in a coordinated series of changes of physiological gastroentero–pancreatic functions and confirm that the physical state of the meal plays an important role in modulating endocrine and metabolic responses to food.

To verify the influence of food consistency on satiety mechanisms we evaluated the effects of the same meal in solid–liquid (SM) and homogenized (HM) form on satiety sensation, gastric emptying rate and plasma cholecystokinin (CCK) concentration. Eight healthy men, aged 21-28 (mean 24·5) years were given two meals (cooked vegetables 250 g, cheese 35 g, croutons 50 g and olive oil 25 g, total energy 2573 kJ, with water 300 ml) differing only in physical state: SM and HM. The subjects consumed the meals in randomized order on non-consecutive days. The sensations of fullness, satiety and desire to eat were evaluated by means of a questionnaire, gastric emptying was assessed by ultrasonographic measurement of antral area, and plasma CCK concentration was measured by radioimmunoassay. The vegetable-rich meal was significantly more satiating (P < 0·05) when in the HM form than when eaten in a SM state. Furthermore, the overall gastric emptying time was significantly slowed (255 (sem 11) min after HM v. 214 (sem 12) min after SM; P < 0·05) and CCK peak occurred later (94 (sem 12) min after HM v. 62 (sem 11) min after SM; NS) when the food was consumed in the HM form. Independently of the type of meal, antral area was significantly related to fullness sensations (r2 0·46, P = 0·004). These results demonstrate that meal consistency is an important physical food characteristic which influences both gastric emptying rate and satiety sensation. Moreover, the relationship observed between antral area and fullness sensation confirms that antral distension plays a part in the regulation of eating behaviour.