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Item Determinants of the postprandial triglyceride response to a high-fat meal in healthy overweight and obese adults(Springer Nature, 2021-09) Wilson, Stephanie M.; Maes, Adam P.; Yeoman, Carl J.; Walk, Seth T.; Miles, Mary P.Background. Dyslipidemia is a feature of impaired metabolic health in conjunction with impaired glucose metabolism and central obesity. However, the contribution of factors to postprandial lipemia in healthy but metabolically at-risk adults is not well understood. We investigated the collective contribution of several physiologic and lifestyle factors to postprandial triglyceride (TG) response to a high-fat meal in healthy, overweight and obese adults. Methods. Overweight and obese adults (n = 35) underwent a high-fat meal challenge with blood sampled at fasting and hourly in the 4-hour postprandial period after a breakfast containing 50 g fat. Incremental area under the curve (iAUC) and postprandial magnitude for TG were calculated and data analyzed using a linear model with physiologic and lifestyle characteristics as explanatory variables. Model reduction was used to assess which explanatory variables contributed most to the postprandial TG response. Results. TG responses to a high-fat meal were variable between individuals, with approximately 57 % of participants exceeded the nonfasting threshold for hypertriglyceridemia. Visceral adiposity was the strongest predictor of TG iAUC (β = 0.53, p = 0.01), followed by aerobic exercise frequency (β = 0.31, p = 0.05), insulin resistance based on HOMA-IR (β = 0.30, p = 0.04), and relative exercise intensity at which substrate utilization crossover occurred (β = 0.05, p = 0.04). For postprandial TG magnitude, visceral adiposity was a strong predictor (β = 0.43, p < 0.001) followed by aerobic exercise frequency (β = 0.23, p = 0.01), and exercise intensity for substrate utilization crossover (β = 0.53, p = 0.01). Conclusions. Postprandial TG responses to a high-fat meal was partially explained by several physiologic and lifestyle characteristics, including visceral adiposity, insulin resistance, aerobic exercise frequency, and relative substrate utilization crossover during exercise.Item Post-prandial serum concentrations of Trimethylamine-N-oxide in overweight and obese adults with low and high systemic inflammation(Montana State University - Bozeman, College of Education, Health & Human Development, 2018) Wilson, Stephanie Michelle; Chairperson, Graduate Committee: Mary P. MilesPurpose: Elevated trimethylamine-N-oxide (TMAO) levels have been implicated in the development of atherosclerosis. The impact of a high-fat meal on the post-prandial TMAO response in healthy overweight and obese adults was explored, accounting for additional variables that may affect the rate of TMAO conversion. Methods: Forty overweight and obese men and women participated in a high-fat meal challenge containing 50 g fat. Blood samples were collected at fasting and hourly in the 4 hours after meal ingestion and tested for concentrations of TMAO, liver enzymes, lipids, creatinine, insulin, and inflammatory markers. An initial mixed-effects model was constructed to analyze TMAO changes in participants who classified as having low or high levels of systemic inflammation accounting for factors that may influence TMAO concentrations. Backward refinement of the initial model was performed based off p-values. Results: Model refinement found that the log TMAO response was best explained by inclusion of estimated glomerular filtration rate (eGFR), insulin over time, a linear interaction between time and inflammation phenotype, and random effects on subject. Log TMAO after the meal was not different between inflammation phenotypes (p = 0.33). Estimated GFR was the most important determinant in the log TMAO response (p = 0.03), with lower log TMAO observed with higher eGFR values. In conclusion, serum TMAO concentrations during a high fat-meal challenge were strongly determined by eGFR, but not by fasting inflammation status.