Macronutrients and obesity: views, news and reviews

Abstract

Profound changes in macronutrient composition of food have taken place since the agricultural revolution, leading to a higher dietary intake of carbohydrates at the expense of protein, and a dramatically increased intake of n-6 polyunsaturated fatty acids (PUFAs) at the expense of n-3 PUFAs. This review focuses on how macronutrients impact on molecular processes central to appetite regulation and energy homeostasis. We discuss the effects on transcription factors, implicated as key players in adipocyte differentiation and function, including PPARs, sterol regulatory element binding proteins and liver X receptors. Furthermore, as energy homeostasis is to a large extent orchestrated by the gut–brain axis, we discuss key hormones involved in the regulation of energy balance and appetite. Obesity is rapidly climbing the WHO’s top ten global health problem list. As increased adipose tissue mass is associated with increased adipocyte size and number, understanding of adipocyte differentiation and function in terms of regulation of metabolism is important to curb the obesity epidemic. Genetics may account for an individual’s predisposition to obesity, but habitual food intake in excess of energy expenditure is probably a primary factor in obesity development. In view of huge changes in the human diet and the emerging knowledge concerning the ability of dietary macronutrients to directly or indirectly act as signaling molecules, we review research aimed at elucidating molecular mechanisms governing the effects of macronutrients on the differentiation and function of white fat cells. Furthermore, as nutrient homeostasis is to a large extent orchestrated by the gut–brain axis, we discuss key hormones involved in the regulation of energy balance and appetite. Since a large proportion of the experimental work has been performed using rodent models, including numerous informative transgenic models, this review primarily focuses on data obtained from studies on rodents, but in addition, we also refer readers to