Familial influences and obesity-associated metabolic risk factors contribute to the variation in resting energy expenditure: the Kiel

Background:Alowmetabolicratemaybeinheritedandpredispose to obesity, whereas a higher metabolic rate in obesity may be acquired by obesity-associated cardiometabolic risk. Objective: We aimed to explain the interindividual variation in resting energy expenditure (REE) by assessing 1) the association between REE and body composition, thyroid hormones, and obesity-related cardiometabolic risk factors, and2) the familial (genetic and environmental) contribution to REE. Design: REE and metabolic risk factors (ie, blood pressure and plasmainsulin,glucose,andC-reactiveproteinconcentrations)were assessed in 149 two- or three-generation families, including at least one overweight or obese member. Heritability of REE, respiratory quotient (RQ), thyroid hormones [thyrotropin (TSH), free triiodothyronine (FT3) and free thyroxine (FT4)], and body composition (fat-free mass and fat mass) were estimated by using variance components–based quantitative genetic models. Results:REEadjustedforbodycomposition,sex,andage(REEadj) significantly correlated with systolic and diastolic blood pressure, plasma insulin and glucose concentrations, and the homeostasis model assessment (HOMA) (r 0.14–0.31, P 0.05). Thyroid hormoneshadamodestinfluenceonREEvarianceonly.Heritability was0.300.07forREEadjand0.290.08forREEafteradditional adjustment for thyroid hormones and metabolic risk. Furthermore, heritability was estimated to be 0.220.08 for RQ, 0.370.08 for TSH,0.680.06forFT4,and0.690.05forFT3(allsignificantly larger than zero). Conclusions: Obesity-related cardiometabolic risk factors contribute to interindividual variation in REE, with hypertension and insulin resistance being associated with a higher REE. REE was mod