(P16-015-23) Discordance Between Postprandial Appetite Hormone Responses and Energy Intake in Humans

Objectives: To explore the effects of diet composition on postprandial appetite hormone responses to isocaloric diet-specific meals and measure subsequent energy intake.

Methods: In an inpatient setting, 20 healthy adults (mean ± SEM; age 30 ± 1 y, BMI 27.8 ± 1.3 kg/m²) consumed a low-fat diet (LF; 10% fat, 75% carbohydrate) and a low-carbohydrate diet (LC; 10% carbohydrate, 75% fat) for 2 weeks each, in a randomized crossover design without a washout. Near the end of the second week of each diet, after an overnight fast, participants consumed isocaloric breakfast meals (30% of estimated energy requirements) matching the macronutrient composition of each diet. Postprandial appetite hormones were measured for 6 hours. Ad libitum energy intake was measured for the rest of the day (lunch, dinner, and snacks).

Results: The LC test meal resulted in greater mean postprandial plasma concentrations of active GLP-1 (LC: 6.44 ± 0.78 pg/mL, LF: 2.46 ± 0.26 pg/mL; p < 0.0001), GIP (LC: 578 ± 60 pg/mL, LF: 319 ± 37 pg/mL; p=0.0004), and PYY (LC: 65.6 ± 5.6 pg/mL, LF: 50.7 ± 3.8 pg/mL; p=0.02) whereas total ghrelin (LC: 184 ± 25 pg/mL, LF: 261 ± 47 pg/mL; p=0.02), active ghrelin (LC: 91 ± 9 pg/mL, LF: 232 ± 28 pg/mL; p < 0.0001), and leptin (LC: 26.9 ± 6.5 ng/mL, LF: 35.2 ± 7.5 ng/mL; p=0.03) were lower as compared to the isocaloric LF test meal. After the breakfast meal test, participants ate more ad libitum energy during the LC diet at lunch (244 ± 85 kcal; p=0.01) and dinner (193 ± 86 kcal; p=0.04), without a detectable change in energy from snacks (114 ± 63 kcal; p=0.09), resulting in a greater total energy intake over the rest of the day compared to LF (551 ± 103 kcal; p < 0.0001). There were no significant correlations between mean postprandial appetite hormone responses and subsequent ad libitum energy intake (all p>0.15).

Conclusions: Postprandial GLP-1, GIP, and PYY were greater following the LC meal compared to an isocaloric LF meal, whereas total and active ghrelin were lower. Although the observed differences in postprandial appetite hormones would be expected to reduce appetite and subsequent ad libitum energy intake following the LC diet, the opposite was observed, suggesting that ad libitum energy intake was more likely influenced by other diet differences.

Funding Sources: Intramural Research Program of the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health