Increased Postprandial Metabolic Flexibility is Associated with Higher Body Fat Percentages in Healthy Young Adults

PURPOSEBecause higher adiposity is associated with cardiometabolic disease, we assessed the relationship between body composition (body fat percentage; BF%) and postprandial metabolic flexibility. METHODSYoung adults (n = 27, n = 15 females, BMI = 27.1 {+/-} 4.5; BF% = 30.4 {+/-} 8.7) without overt pathology completed a 100g oral glucose tolerance test (OGTT). Indirect calorimetry before (fasting) and following (30, 60, 90, 120 min) consumption was used to calculate respiratory exchange ratio (RER) and oxidation of carbohydrates (CHO) and fats (FOX). Serum and plasma were collected at corresponding time points and analyzed for blood glucose, insulin, and NEFAs. Data from individuals with normal weight were compared to those with overweight/obesity by two-way repeated measures ANVOA. The effect of BF% on postprandial metabolism was tested via linear mixed models while adjusting for potential confounders. RESULTSDuring the OGTT, blood glucose, serum insulin, plasma lactate, RER, and CHO all significantly increased while plasma NEFAs and whole-body FOX decreased (all p<0.05). BF% modified the relationship between postprandial RER and time (p = 0.019) as well as postprandial CHO and time (p = 0.023) without an effect of BF% on FOX; individuals with higher BF% increase their RER and CHO faster and to a greater extent than those with lower BF%. CONCLUSIONBody fat percentage is associated with greater postprandial metabolic flexibility during an OGTT in young adults. Despite increased adiposity, metabolic flexibility may be preserved, representing a compensatory adaptation to decreased glucose storage in the postprandial period.