Mapping body fat distribution: A key step towards the identification of the vulnerable patient?

Abstract

Although excess body fat is a significant health hazard, estimation of body fat content with the body mass index may not adequately reflect the amount of atherogenic adipose tissue (AT), i.e. visceral and ectopic fat. As opposed to subcutaneous AT that supposedly acts as a metabolic sink buffering excess dietary energy, visceral or intra-abdominal AT depots respond to several external stimuli that trigger lipolysis and secretion of free fatty acids (FFAs). Reaching the liver, FFAs accumulate in the liver and, over time, promote a chronic condition known as non-alcoholic fatty liver disease (NAFLD). The liver of the typical NAFLD patient secretes large amounts of very-low-density lipoproteins, the lipid content of which may accumulate in additional organs (skeletal muscle, heart, and pancreas). Here, we review the evidence emerging from functional and population studies that point towards an important role of ectopic fat accumulation in the pathophysiology of type 2 diabetes and cardiovascular disease. We conclude that although patients with impaired glycemic control or type 2 diabetes are at increased cardiovascular disease (CVD) risk, estimating cardiovascular risk goes wellbeyond the assessment of glycemic control and traditional CVD risk factors, and the estimation of visceral/ectopic fat deposition via readily available imaging techniquesshould be considered.

Key words::

• Atherosclerosis
• computed tomography
• ectopic fat accumulation
• glucose–insulin homeostasis
• imaging
• inflammation
• insulin resistance
• magnetic resonance imaging
• type 2 diabetes
• visceral obesity

Acknowledgements

The work of the authors has been supported by research grants from the Canadian Institutes of Health Research, the Heart and Stroke Foundation, and by the Foundation of the Quebec Heart Institute. Dr Larose is a researchscholar of the Fonds de la Recherche en Santé du Québec (FRSQ). Dr Després is the Scientific Director of the International Chair on Cardiometabolic Risk, which is based at the Université Laval. Benoit J. Arsenault is supported by a post-doctoral fellowhip from the Fonds de la Recherche en Santé du Québec and the Fondation de l’Institut universitaire de cardiologie et de pneumologie de Québec.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.