Impact of a FTO gene risk variant on variables of energy metabolism in adults with obesity class 2 and 3

Abstract Purpose The metabolic consequences of carrying a FTO obesity-promoting risk allele have not been fully elucidated and may be confounded by obesity per se . Against this background, we investigated the impact of FTO allele (SNP rs9939609) on fasting and postprandial energy expenditure and fasting substrate expenditure in a study population of uniformly and similarly obese individuals. Procedures We studied a similar number of participants with BMI classes 2–3 (median BMI 42.8 kg/m 2 ) who were either homozygote for the non-risk allele TT (n = 33, numbers increased by enrichment), heterozygote (AT) (n = 32), or homozygote for the risk allele AA (n = 35). Major findings Basal metabolic rate and postprandial energy expenditure did not differ between FTO-groups. However, fasting respiratory quotient (RQ) was increased in those carrying ≥1 risk allele (p = 0.008), whereas postprandial RQ was not. Conclusion In this study population, the FTO-risk allele associates with fasting reduced fat and increased carbohydrate oxidation.