Jessica Danaher, Christos G Stathis and Matthew B Cooke
Royal Melbourne Institute of Technology University, Australia
Victoria University, Australia
Swinburne University of Technology, Australia
Posters & Accepted Abstracts: J Hepatol Gastroint Dis
Metabolic flexibility refers to the ability of the muscle to effectively switch between substrates supplying energy based on availability. Although a decline in FTO transcription has been associated with alterations in glucose and lipid metabolism, it is unknown if this subsequently influences metabolic flexibility. This study investigated the influence of FTO rs9939609 genotype (variant alleles: AA, AT and TT) and BMI (lean: <25 kg/m2 and overweight: >25 kg/m2) on metabolic and respiratory markers of substrate oxidation in the basal state and following a glucose-stimulated dietary challenge. Apparently healthy, sedentary males and females aged 20-50 years (n=147) completed a single experimental session designed to (1) assess pre-prandial plasma glucose and serum insulin concentrations, Respiratory Exchange Ratio (RER) and substrate oxidation following a 10-12 hours overnight fast and (2) assess the physiological responses of these variables following an Oral Glucose Load (OGL) challenge. Metabolic flexibility (measured as �?RER over time) was slower in overweight individuals compared to lean individuals (p=0.009), but not different between FTO genotypes (p>0.05), independent of BMI. Overweight individuals demonstrated lower pre-prandial fat oxidation (p=0.012) and elevated pre-prandial glucose oxidation (p=0.031) compared to lean individuals. No differences in pre-prandial or post-prandial substrate oxidation were observed between FTO genotypes (p>0.05). Plasma glucose was significantly increased post OGL (p<0.001), however, no differences were observed when separating participants by BMI or FTO genotype (p>0.05). Significantly greater insulin resistance was observed in overweight individuals when compared to lean individuals (p=0.007), whilst insulin resistance and sensitivity were similar between FTO genotypes (p>0.05). An acute nutritional stimulus produced a slower metabolic flexibility and higher insulin resistance in individuals with an overweight BMI but did not produce different responses between FTO allelic variants.
Jessica Danaher has completed her PhD at Victoria University in Human Obesity Genetics and Skeletal Muscle Metabolism using nutrition and exercise stressors. She also pursued Masters of Dietetics at Deakin University and is now an Accredited Practicing Dietitian. Her previous roles include Clinical Dietitian at St Vincent's Hospital, Casual Research Fellow at Deakin University, Sessional Academic at Victoria University and Victorian Clinical Director of Health Promotion for Special Olympics Australia. She is currently a Lecturer/Early Career Development Fellow in Nutrition at RMIT University.