ESPE Yearbook of Paediatric Endocrinology

Lancet Diabetes Endocrinol 2019; 7: 231–40. DOI: 10.1016/S2213-587(19)30026-9

• This study uses quantitative data from reputable global data sets to demonstrate that the epidemiology of obesity can be framed as a conceptual model of obesity transition.

• A new framework to classify the obesity epidemic is proposed that may assist policy makers and researchers to improve surveillance and develop targeted preventative obesity interventions.

As pediatricians and endocrinologists, we tend to consider the interplay of biological factors such as genetics, epigenetics and the microbiome, and environmental factors such as sociocultural and economic conditions, policies and the built environment as the most important determinants of obesity. While these factors likely account for the varying distribution and intensity of obesity between geographical regions, it remains that obesity has become a global epidemic across populations.

In this paper, akin to the well-known concept of the epidemiological transition, the authors develop the concept of obesity transition whereby populations predictably transition through four distinct phases of obesity over time: In stage 1, obesity is overall low but at around 5% highest in women, greater in adults than in children, and greater in persons of high vs. low socioeconomic status (SES). All very large low-income countries such as India are currently at this stage. In stage 2, the prevalence increases to 25–40% among adults and to around 10% among children, and the gap between sexes and between SES narrows. All countries that were at stage 1 in 1975 (e.g., Mexico) were at stage 2 by 2016. In stage 3, the adult prevalence stalls while childhood obesity increases slightly, however the sex gap closes and there is a reversal in SES differences. Most European and North American countries are at this stage. Stage 4 is a hypothetical stage, yet to be attained by any country, where the obesity prevalence curve flattens in children, such that eventually leaner children enter adulthood, leading to eventual reductions in the prevalence of adult obesity. Trends towards this stage may be seen in some high-SES subpopulations.

This new concept provides the means for future identification of obesity transition stages in any given population, anticipation of obesity risk in subpopulations, and introduction of proactive measures that may attenuate transition. For instance, understanding a potential mismatch between today’s high carbohydrate and high calorie diet and the origin of a population (hunter-gatherers with low insulin sensitivity vs farmers with high insulin sensitivity) might help design individual-specific therapeutic approaches (low carbohydrate diets vs low calorie diets) (2). If future research can identify factors that determine the underlying drivers of transition between stages, might populations be able to attain stage 4?

References: 1. Stanaway JD, Afshin A, Gakidou E, et al. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990, 2013, 2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet 2018; 392: 1923–94.

2. Hochberg Z. An Evolutionary Perspective on the Obesity Epidemic. Trends Endocrinol Metab. 2018 Dec;29(12):819–826.