Increased Postprandial Metabolic Flexibility is Associated with Higher Body Fat Percentages in Healthy Young Adults
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PURPOSE
High levels of adiposity are associated with an increased risk for chronic cardiometabolic disease. Adipose tissue is a critical metabolic tissue during the postprandial (feeding) period. We sought to assess the relationship between body composition (body fat percentage) and measures of postprandial metabolic flexibility in otherwise healthy young adults.
METHODS
Young adults (n = 27, n = 15 females) of varying body compositions (BMI = 27.1 ± 4.5; Body Fat (BF)% = 30.4 ± 8.7) but without overt pathology completed a 100g oral glucose tolerance test (OGTT). Indirect calorimetry was conducted before (fasting) and following (30, 60, 90, 120 min) consumption of the glucose beverage. Serum and plasma were collected at corresponding time points and analyzed for blood glucose, insulin, non-esterified fatty acids, and inflammatory markers. Linear mixed models were used to test for the effect of body composition on postprandial metabolism over time while controlling for sex, age, fasting metabolism, measures of insulin sensitivity, visceral adipose tissue volume, and the repeated measures design.
RESULTS
As expected, there was a significant (p < 0.05) increase in blood glucose, serum insulin, RER, and CHO with concomitant decreases in plasma NEFAs and whole-body FOX during the OGTT. Using mixed effects models, BF% modified the relationship between postprandial RER and time ( β = -0.133, p = 0.019), as well as postprandial CHO and time ( β = -0.134, p = 0.023) such that individuals with higher BF% increase their RER and CHO at a greater rate and to a greater extent than those with lower BF%. There was no evidence that BF% modifies the relationship between FOX and time.
CONCLUSION
We demonstrate that a higher body fat percentage is associated with greater postprandial metabolic flexibility (RER and CHO) during an OGTT in young adults without overt metabolic pathology. Metabolic flexibility in this sample may be preserved and represents a compensatory adaptation to decreased glucose storage in the anabolic, postprandial period.
