(P15-005-23) Effects of Early Time-Restricted Eating on Intestinal Energy Absorption in Healthy Adults

Objectives: Aligning energy intake with the circadian rhythm and extending periods of fasting within a 24-h cycle improves whole-body metabolism. However, it is unknown if these improvements are related to changes in intestinal nutrient absorption (i.e., digestibility). This study aimed to determine the impact of early time-restricted eating (eTRE) on energy and macronutrient digestibility, gastrointestinal function, and cardiometabolic health.

Methods: In this crossover, controlled feeding trial, healthy adults [n=16 (8 m/8 f), 31 ± 5 y, 23.8 ± 3.4 kg/m²] were randomized to follow an isocaloric, weight maintenance eTRE (calories consumed 0800-1400) or control eating schedule (calories consumed 0800-2000). After a 3-d acclimation to the diet and eating schedule, all stool and urine were collected for 3 d. Energy content of the diet, stool, and urine was measured by bomb calorimetry and energy digestibility calculated. Additional outcomes included macronutrient digestibility, whole and segmental gut transit time, gastrointestinal hydrogen concentrations and microbial composition, mean 24-h glucose concentrations and variability, and fasting and postprandial glucose, insulin, and lipid concentrations and metabolomic profiling.

Results: eTRE had no impact on energy or macronutrient digestibility or gastrointestinal transit time, hydrogen concentration, or microbial composition compared to control. eTRE decreased mean 24-h glucose (eTRE: 94 ± 11 vs. control: 101 ± 12 mg/dL; P< 0.0005), fasting glucose (87 ± 6 vs. 94 ± 7 mg/dL; P=0.01), insulin (10.1 ± 3.9 vs. 13.5 ± 7.4 µIU/mL; P=0.008), HOMA-IR (2.2 ± 0.9 vs. 3.2 ± 1.7; P=0.001), VLDL-C (14.6 ± 6.9 vs. 16.0 ± 6.1 mg/dL; P=0.03), and triglycerides (73 ± 34 vs. 80 ± 30 mg/dL; P=0.03) compared to control. Fasting and postprandial metabolomic profiles, postprandial glucose, insulin, and lipid levels did not differ between eTRE and control.

Conclusions: eTRE improved markers of cardiometabolic health, including glucose regulation, compared to the control eating schedule. Intestinal energy and macronutrient absorption were not impacted by eTRE, suggesting intestinal absorption does not mediate the cardiometabolic benefits observed with eTRE.

Funding Sources: 2021 Herbalife Nutrition Scholarship, FSU Council on Research & Creativity<br><br>DISCLAIMER: Authors’ views do not reflect official DoD or Army policy.