Energy intake, ghrelin, and cholecystokinin after different carbohydrate and protein preloads in overweight men.

CONTEXT: Dietary proteins appear to be more satiating than carbohydrate. The mechanism and effect of protein and carbohydrate type are unclear.

OBJECTIVE

The objective of the study is to compare the acute effect of different proteins and carbohydrates on indicators of appetite and appetite regulatory hormones.

DESIGN

This is a randomized cross-over study of four orally consumed preloads followed by blood sampling (+15, 30, 45, 60, 90, 120, 180 min), then a buffet meal.

SETTING

The study was carried out in an outpatient clinic.

PATIENTS AND OTHER

PARTICIPANTS

Nineteen overweight (body mass index 32.1 +/- 0.9 kg/m(2)) men participated.

INTERVENTIONS: Liquid preloads (1 MJ) contained whey (55 g), casein (55 g), lactose (56 g), or glucose (56 g).

MAIN OUTCOME MEASURES: Plasma ghrelin, cholecystokinin (CCK), insulin, glucose and amino acids, gastric emptying rate (plasma paracetamol), appetite rating (visual analog scale), and ad libitum energy intake were the main outcome measures.

RESULTS

Energy intake was 10 +/- 3% higher after the glucose preload compared with lactose and protein preloads (P < 0.05), which were predicted by ghrelin at 120 min (P < 0.05). CCK was 71 +/- 6% higher 90 min after the protein preloads compared with glucose and lactose (P < 0.05), which predicted appetite at 180 min (P < 0.05). There was a small increase in branched chain amino acids after the whey preload compared with casein (P < 0.01), but this was independent of appetite and energy intake.

CONCLUSION

Acute appetite and energy intake are equally reduced after consumption of lactose, casein, or whey compared with glucose, which was consistent with differences in plasma ghrelin. Higher CCK responses after proteins correlated with satiety but did not affect energy intake.