Ectopic fat: The potential target for obesity management

Abstract

Accumulation of fat at ectopic sites rather than mere increase in body fat can explain almost all metabolic consequences of obesity. Certain characteristics of adipocytes like increased size and ectopic accumulation make them metabolically sick. Hence 'adiposopathy' seems to be more important than just 'adiposity'. Genetic and epigenetic factors, along with intra-uterine factors determine ectopic fat accumulation. These three factors result in low subcutaneous adipose tissue (SAT) volume leading to 'spillover' of excess fat to ectopic sites; determining 'metabolic economy', by creating a 'thrifty phenotype' with calorie excess later in life resulting in 'maladaptation' and excess weight gain. This is particularly important for South Asians who have been found to have low SAT volume and possess a 'thrifty phenotype'. Obesogenic diet and lack of physical activity contribute to ectopic fat deposition by creating a positive energy balance. Increased fructose and trans-fat consumption are important determinants of obesity and ectopic fat deposition. The good news is that ectopic fat is very responsive to treatment, disappearing at a faster rate with minimal weight loss, resulting in improvement in metabolic and organ functions. Physical activity causes negative energy balance and improves 'metabolic flexibility'. Targeting 'ectopic fat' should be the highlight of obesity management today and its primordial prevention should aim at targeting maternal nutrition.