From dearth to excess: the rise of obesity in an ultra-processed food system

Abstract

More people now have obesity than suffer from starvation thanks to our modern food system. Agriculture was transformed over the 20th century by a variety of technological advancements that relied heavily on fossil fuels. In the United States, government policies and economic incentives led to surplus production of cheap inputs to processed food industries that produced a wide variety of heavily marketed, convenient, rewarding, timesaving, and relatively inexpensive ultra-processed foods. The energy available in the food supply increased by much more than the population needs, albeit with large inequities in nutrition security. While most of the rise in per capita food availability during the late 20th and early 21st centuries in the United States resulted in increased food waste, a variety of mechanisms have been proposed by which changes in the increasingly ultra-processed food environment resulted in excess energy intake disproportionately in people genetically susceptible to obesity. As populations continue to grow, substantial investments in coordinated nutrition and agricultural research are needed to transform our current food system to one that relies less on fossil fuels, preserves biodiversity, ensures environmental health, and provides equitable access to affordable, safe and nutritious food that reduces the prevalence of chronic diet-related diseases like obesity. This article is part of a discussion meeting issue ‘Causes of obesity: theories, conjectures and evidence (Part I)’.

Models of body weight and fatness regulation

“…particularly at the weekly level, might be because the timescale over which regulation happens is quite long. Moreover, the fact that we have an obesity epidemic, clearly driven by environmental changes stimulating our intake [109][110][111] and reducing our expenditure [112] seems incompatible with the idea of a set-point system regulating our body weight. This could be explained if for some reason the set-points in different individuals have expanded upwards during the last 70 years or so.…”

“…This slow slide upwards is probably stimulated mostly by greater food intake and the food environment [109][110][111]. There has been debate about whether it has been contributed to by reduced physical activity.…”

Breaking down silos: the multifaceted nature of obesity and the future of weight management

“…For example, the current food environment has experienced an increase in the prevalence of energy-dense, ultra-processed foods [4]. While modern food processing techniques promote the safety of food, enhance micronutrient content, allow for cost-effective dietary diversity across seasons and ensure adequate food supply to support populations, evidence implicates ultra-processed foods in unintentional weight gain, most likely through increased energy intake and altered biochemical pathways [7][8][9][10][11]. Further, innate and learned food preferences and satiety signals can impact how an individual interacts with the food environment [12].…”

“…interaction between biology and environment), possibly because largescale observational studies or interventions with repeated measures of the genetic/biological factors, environmental exposure and weight change are sparse. Interactions between the environment and individual-level contributors, such as the influence of various diets on physiology of body weight, are under continuous investigation [11,13,89,90]. However, waiting to understand the precise mechanisms by which dietary profiles increase body weight (e.g.…”

“…However, waiting to understand the precise mechanisms by which dietary profiles increase body weight (e.g. diets high in ultra-processed foods) may not be necessary to inform prudent interventions [9,11,13,89,90]. Investigation of the social and demographic factors explaining between-person differences in body weight and weight gain at a population-level is needed.…”