If the global epidemic of non-communicable disease (NCD) has a single defining marker, it is seemingly the relentless global increase in body mass index (BMI). At the population level, an increased prevalence of people with high BMI tends to indicate not only higher levels of harmful body fat, but also exposure to other NCD risk factors, such as lipogenenic diets and sedentary behaviour. Within recent decades, the global prevalence of low BMI in adults has steadily fallen, whereas that of high BMI, reflecting obesity, has systematically increased in most countries. Increasingly, rising BMI is observed in younger age groups too, though rates of child undernutrition remain higher than in adults [1]
