1 3 Eur J Nutr DOI 10.1007/s00394-015-0993-z ORIGINAL CONTRIBUTION Age-related changes in basal substrate oxidation and visceral adiposity and their association with metabolic syndrome Mario Siervo 1,2 · Jose Lara 1 · Carlos Celis-Morales 1 · Michele Vacca 2 · Clio Oggioni 1 · Alberto Battezzati 3 · Alessandro Leone 3 · Anna Tagliabue 4 · Angela Spadafranca 3 · Simona Bertoli 3 Received: 17 April 2015 / Accepted: 6 July 2015 © Springer-Verlag Berlin Heidelberg 2015 was measured by bioelectrical impedance. Abdominal sub- cutaneous fat and VAT were measured by ultrasonography. MetSyn was diagnosed using harmonised international criteria. Multivariate linear and logistic regression models were utilised. Results VAT increased with age in both men (r = 0.31, p < 0.001) and women (r = 0.37, p < 0.001). Basal RQ was not significantly associated with age (p = 0.49) and VAT (p = 0.20); in addition, basal RQ was not a sig- nificant predictor of MetSyn (OR 3.31, 0.57–19.08, p = 0.27). VAT was the primary predictor of MetSyn risk in a fully adjusted logistic model (OR 4.25, 3.01–5.99, p < 0.001). Conclusions Visceral adiposity remains one of the most important risk factors for cardiometabolic risk and is a significant predictor of MetSyn. Post-absorptive sub- strate oxidation does not appear to play a significant role in age-related changes in body composition and cardio- metabolic risk, except for a correlation with triglyceride concentration. Keywords Indirect calorimetry · Substrate oxidation · Ageing · Body composition · Metabolic risk Introduction Ageing is characterised by a decline in total energy expenditure (EE) including resting EE, dietary-induced thermogenesis and activity EE [1, 2]. These changes may predispose to weight gain and accumulation of abdominal fat [3], which are closely linked to the pathogenesis of car- diometabolic, musculoskeletal and neuro-degenerative dis- eases such as coronary heart disease, metabolic syndrome (MetSyn) or Alzheimer’s disease [4]. Abstract Purpose Ageing is directly associated with visceral fat (VAT) deposition and decline of metabolically active cel- lular mass, which may determine age-related shifts in sub- strate oxidation and increased cardiometabolic risk. We tested whether VAT and fasting respiratory quotient (RQ, an index of macronutrient oxidation) changed with age and if they were associated with increased risk of metabolic syndrome (MetSyn). Methods A total of 2819 adult participants (age range: 18–81 years; men/women: 894/1925) were included; we collected history, anthropometric measures, biochemis- try, smoking habits, and physical activity. The body mass index range was 18.5–60.2 kg/m 2 . Gas exchanges (VO 2 and VCO 2 ) were measured by indirect calorimetry in fast- ing conditions, and RQ was calculated. Body composition Electronic supplementary material The online version of this article (doi:10.1007/s00394-015-0993-z) contains supplementary material, which is available to authorized users. * Mario Siervo mario.siervo@ncl.ac.uk 1 Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne NE4 5PL, UK 2 MRC Human Nutrition Research, Fulbourn Road, Cambridge CB1 9NL, UK 3 International Center for the Assessment of Nutritional Status (ICANS), Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, Sandro Botticelli, 21, 20133 Milan, Italy 4 Human Nutrition and Eating Disorders Research Centre, Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Via Bassi, 21, 27100 Pavia, Italy