Ultra-processed Food and Obesity: What Is the Evidence?

Abstract

Purpose of Review Obesity is a growing global healthcare concern. A proposed driver is the recent increase in ultra-processed food (UPF) intake. However, disagreement surrounds the concept of UPF, the strength of evidence, and suggested mechanisms. Therefore, this review aimed to critically appraise the evidence on UPF and obesity. Recent Findings Observational studies demonstrate positive associations between UPF intake, weight gain, and overweight/obesity, more clearly in adults than children/adolescents. This is supported by high-quality clinical data. Several mechanisms are proposed, but current understanding is inconclusive. Summary Greater UPF consumption has been a key driver of obesity. There is a need to change the obesogenic environment to support individuals to reduce their UPF intake. The UPF concept is a novel approach that is not explained with existing nutrient- and food-based frameworks. Critical analysis of methodologies provides confidence, but future observational and experimental research outputs with greater methodological rigor will strengthen findings, which are outlined.

Data_Sheet_1.docx

“…In fact, according to the study by Hall (28), the weekly cost to prepare a diet of 2000 Kcal/day consisting of ultraprocessed foods was US$ 106, compared to US$ 151 for an unprocessed diet. Therefore, it has been suggested that policies to reduce UPF intake take into account the most vulnerable groups to avoid deepening economic, health, and social inequalities (33). Strategies have been proposed, such as including these groups in food assistance programs to improve access to natural and minimally processed foods (2), as well as reformulating UPFs.…”

“…For example, the extrusion and retrogradation of starch affect the availability of carbohydrates, while particle size and viscosity influence glycemic response, whose postprandial level can impact appetite and fat storage in the liver and skeletal muscle, which is associated with the development of insulin resistance (47,57). Furthermore, ultra-processing modifies the texture of foods, making them softer and easier to consume, promoting continuous and unconscious eating behaviors (46), and a faster energy intake that affects satiety, transit time, digestibility, and nutrient bioavailability (2,33). These relationships could be due to inadequate signaling of satiety sensations to the brain, the release of hormones that regulate hunger and satiety, and a shorter gastric emptying time that increases the speed at which nutrients are released and absorbed in the body (58,59).…”

“…However, reviews of observational studies have limitations, such as the inclusion of studies that use different methods to assess UPF intake (67), different models for adjusting covariates (67, 68), heterogeneous doses of intake between higher and lower exposure groups (1,68), different classification systems and reference units (1,46), as well as variable follow-up periods (69). Therefore, considering the growing importance of UPFs in shaping global nutrition policies and guidelines, high-quality clinical trials are needed to overcome these limitations and define causality mechanisms that cannot be solely inferred from observational studies (33).…”

“…Some countries already include this recommendation as part of their dietary guidelines or have implemented strategies to reduce their consumption, such as the use of nutritional warning labels, selective taxes, marketing restrictions, or bans in schools (67). However, these recommendations are primarily based on results from prospective observational studies with methodological limitations and not designed to establish causal mechanisms (33). This reliance on observational study results to support nutritional recommendations is common (29) and often reflects the difficulty of developing longterm dietary clinical trials (32,67).…”

“…From the perspective of health and nutrition policies, it is necessary for governments to promote measures to encourage the consumption of healthy natural or minimally processed foods, making them more available, valued, and (83). Likewise, it should be recognized that UPFs play a central role in food systems and can be drivers of diet quality in contexts where nutrient-rich foods are scarce or have limited access (33,83). In this sense, policies to limit UPF consumption should be accompanied by strategies that minimize any negative impact on the food security of vulnerable groups (33), including regulations to facilitate the reformulation of UPFs, especially those aimed at replacing processed, refined, and reconstituted ingredients with intact or minimally processed ingredients (83).…”