title: Vitamin D status and insulin sensitivity are novel predictors of resting metabolic rate: a cross-sectional analysis in Australian adults.
abstract: OBJECTIVE
  Resting metabolic rate (RMR) accounts for two-thirds of the total energy expenditure in sedentary individuals. After accounting for traditional factors, there still remains a considerable unexplained variance in RMR. There is a pandemic of obesity and metabolic syndrome (MetS) which coexists with a high prevalence of vitamin D insufficiency. The aim of this study was to evaluate the potential effects of vitamin D status, insulin sensitivity (IS) and the metabolic syndrome (MetS) on RMR in Australian adults.
  
  
  METHODS
  RMR, respiratory quotient (RQ), McAuley's insulin sensitivity index, fat mass (FM), fat-free mass (FFM) and vitamin D status were assessed in Australian adults. The presence of MetS was evaluated by current standard criteria. Predictors of RMR were examined through multiple linear regression based on stepwise and backward regression approaches with attention to multi-collinearity. All analyses were conducted on SPSS version 21.
  
  
  RESULTS
  One hundred and twenty-seven participants (45 men, 82 women), aged 53.4 ± 11.7 years and BMI 31.9 ± 5.2 kg/m(2), were included. Forty-one subjects were insufficient in vitamin D status (<50 nmol/L), and 75 participants had the MetS. A parsimonious regression model explained 85.8 % of RMR and was given by: RMR (kJ/d) = 1931 + 83.5 × FFM (kg) + 29.5 × FM (kg) + 5.65 × 25(OH)D (nmol/L) - 17.6 × age (years) - 57.51 × IS.
  
  
  CONCLUSIONS
  Vitamin D status and IS are novel independent predictors of RMR in adults. Future studies could validate a causal role for these factors in human energy metabolism.
authors: Nutrition, Dietetics and Food Technology, School of Public Health, Curtin Health Innovation Research Institute-Metabolic Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6102, Australia.
authors: E K
authors: EK
authors: Calton
authors: Nutrition, Dietetics and Food Technology, School of Public Health, Curtin Health Innovation Research Institute-Metabolic Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6102, Australia.
authors: K
authors: K
authors: Pathak
authors: Nutrition, Dietetics and Food Technology, School of Public Health, Curtin Health Innovation Research Institute-Metabolic Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6102, Australia. m.soares@curtin.edu.au.
authors: M J
authors: MJ
authors: Soares
authors: Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, Curtin University, Perth, WA, 6102, Australia.
authors: H
authors: H
authors: Alfonso
authors: School of Biomedical Sciences, Curtin Health Innovation Research Institute-Biosciences, Faculty of Health Sciences, Curtin University, Perth, WA, 6102, Australia.
authors: K N
authors: KN
authors: Keane
authors: School of Biomedical Sciences, Curtin Health Innovation Research Institute-Biosciences, Faculty of Health Sciences, Curtin University, Perth, WA, 6102, Australia.
authors: P
authors: P
authors: Newsholme
authors: Optimal Nutrition and Exercise, St John of God Medical Clinic and Wexford Medical Centre, 100 Murdoch Drive, Murdoch, WA, 6150, Australia.
authors: N K
authors: NK
authors: Cummings
authors: General Practice and Primary Care Research Unit, School of Medicine, The University of Notre Dame Australia, 19 Mount Street, Fremantle, WA, 6959, Australia.
authors: W
authors: W
authors: Chan She Ping-Delfos
authors: School of Biomedical Sciences, Curtin Health Innovation Research Institute-Biosciences, Faculty of Health Sciences, Curtin University, Perth, WA, 6102, Australia.
authors: A
authors: A
authors: Hamidi
mesh_terms: D050154:Adiposity; D000328:Adult; D000368:Aged; D001315:Australia; D001481:Basal Metabolism; D001794:Blood Pressure; D015992:Body Mass Index; D001835:Body Weight; D002153:Calorimetry, Indirect; D003430:Cross-Sectional Studies; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D014807:Vitamin D / Q000097:blood*
chemical_list: D014807:Vitamin D
keywords: Insulin sensitivity; Metabolic syndrome; Resting metabolic rate; Vitamin D