Tasty food—does it make us overeat?

Aim of the study: This first paper in a three-part Lancet Series combines narrative and systematic reviews with original analyses and meta-analyses to assess three hypotheses concerning a dietary pattern based on ultra-processed foods.

Results: The second-that this pattern results in deterioration of diet quality, especially in relation to chronic disease prevention-is confirmed by national food intake surveys, large cohorts, and interventional studies showing gross nutrient imbalances; overeating driven by high energy density, hyper-palatability, soft texture, and disrupted food matrices; reduced intake of health-protective phytochemicals; and increased intake of toxic compounds, endocrine disruptors, and potentially harmful classes and mixtures of food additives. The third and final hypothesis-that this pattern increases the risk of multiple diet-related chronic diseases through various mechanisms-is substantiated by more than 100 prospective studies, meta-analyses, randomised controlled trials, and mechanistic studies, covering adverse outcomes across nearly all organ systems.

Aim of the study: The global increase in obesity has occurred in parallel to a dietary shift from traditional staple foods to ultra-processed foods (UPF), spurring scientific interest in UPF as a driver of the obesity pandemic. Herein, we summarize the current evidence regarding the role of UPF in obesity, with a specific focus on potential biological mechanisms.

Results: The literature strongly supports and corroborates ecological, epidemiological and mechanistic lines of research indicating that dietary patterns high in UPF promote overeating and increase the risk of overweight and obesity. Experimental evidence demonstrates that the soft texture, high energy density and hyperpalatable nutrient combinations of UPF facilitate excessive energy intakes by affecting ingestive behaviours, satiety signalling and food reward systems. Although not fully elucidated, it is plausible that several other UPF attributes (such as emulsifiers, non-nutritive sweeteners, acellular nutrients, and contaminants from processing and packaging materials) contribute to their obesogenic effects through a myriad of physiological pathways, including altered absorption kinetics, glycaemic response and the gut microbiota composition and function.

Aim of the study: Background/Objective: Highly palatable foods are pleasurable and motivational stimuli that activate the brain's reward system and can induce overeating in the absence of physiological needs. This study investigated how different access patterns to a cafeteria diet influence food intake, body weight-related parameters, and metabolic and neurobehavioral outcomes.

Results: All cafeteria-fed rats displayed anxiety-like behavior, and all groups preferred sucrose except the continuous-access group. Molecular analyses revealed region-specific differences in gene expression related to neuroplasticity, stress response, and epigenetic regulation that varied with access pattern and predictability. Conclusions: Our results suggest that, beyond diet composition, the pattern and predictability of food access are key determinants of feeding behavior. Intermittent access increases the motivational value of the cafeteria diet, promoting overeating and driving reward- and stress-related neuroadaptations with potential metabolic and mental health implications.

Aim of the study: The consumption of highly palatable ultra-processed foods (UPFs), enriched in sugar, saturated fat, and salt, increases the risk of morbidity and mortality by inducing obesity, type 2 diabetes (T2DM), cardiovascular disease, and cancer.

Results: The duration of UPF exposure significantly influenced glucose metabolism and insulin sensitivity. A 10-day UPF diet was associated with lower fasting blood glucose levels, without higher insulin levels, in both sexes. Females showed early impairment in glucose tolerance. Male mice on UPF30 exhibited elevated systemic IL-6 levels, as well as reduced intestinal expression of Occludin and E-cadherin genes. In females, UPF30 increased TNF-α expression in the gut and increased microbial diversity. Both sexes displayed dysbiosis, with females showing pronounced changes in the proportion between predominant phyla, and males showing more specific changes in bacterial genera. A diet high in UPFs promoted metabolic, inflammatory, and gut microbiota alterations, with effects varying according to exposure duration and biological context, and becoming more pronounced after 30 days.

Aim of the study: A molecular pathway involving compounds found in processed foods and biogenic amines increases food intake and aging in the roundworm C. elegans.

Results: A molecular pathway involving compounds found in processed foods and biogenic amines increases food intake and aging in the roundworm C. elegans.

Aim of the study: The reward value people assign to foods is determined by their intrinsic (food-level) properties and moderated by individual factors such as traits, states and beliefs. There is a need for more systematic, structured analyses of the food-level characteristics that explain cognitions about food reward such as palatability and their risk for reward-driven overeating.

Results: Self-reported food-level attributes explained a further 6-33 % variance in liking and 17-38 % variance in hedonic overeating. UPFs explained 0-7 % additional variance and CFR did not add to the nutritional models. This research demonstrates how nutritional characteristics of foods contribute to self-reported liking and hedonic overeating. Considering people's beliefs about nutrient and sensory attributes can explain more than nutrients alone, and there are negligible additive contributions from CFR or UPFs on food reward.

Aim of the study: Ultra-processed foods (UPFs) have been increasingly implicated in poor physical and mental health outcomes, but their relationship with eating disorder (ED) symptoms remains underexplored. This study aimed to examine the association between UPF consumption and ED symptoms in a large sample of Brazilian adults.

Results: Signs and symptoms of EDs were identified in 39.2% of participants, mainly binge eating (65.7%) and bulimia (18.8%). The mean Nova score for UPF consumption was 3.15 (SD = 2.23). In the covariate-adjusted ANCOVA model, the main effect of ED category was statistically significant (p < 0.001; ω2p = 0.010). Nova scores for UPF consumption were significantly higher in participants with binge eating (M = 3.43, SD = 2.25) and other EDs (M = 3.85, SD = 2.58) compared with those without ED symptoms (M = 2.99, SD = 2.12; p < 0.05). No meaningful interactions with the model covariates were observed. These findings suggest that higher UPF consumption may be more strongly associated with EDs symptoms characterized by loss-of-control eating, underscoring the need for longitudinal research to clarify temporal relationships and mechanisms.

Aim of the study: There is increasing evidence of the impact of ultra-processed foods on multiple metabolic and neurobiological pathways, including those involved in eating behaviors, both in animals and in humans. In this study we aimed to explore ultra-processed foods and their link with disordered eating in a clinical sample.

Results: A total of 70 female and 3 male patients were included in the study; 22 had AN, 25 BN, and 26 BED. Patients with AN reported consuming 55% NOVA-4 foods, as opposed to approximately 70% in BN and BED patients. Foods that were consumed in a binge pattern were 100% ultra-processed. Further research into the metabolic and neurobiological effects of ultra-processed food intake on disordered eating, particularly on binging, is needed.

Aim of the study: Detail recent advancements in the science on ultra-processed food (UPF) addiction, focusing on estimated prevalence rates and emerging health disparities; progress towards identifying biological underpinnings and behavioral mechanisms; and implications for weight management.

Results: Notable developments in the field have included: (1) estimating the global prevalence of UPF addiction at 14% of adults and 15% of youths; (2) revealing health disparities for persons of color and those with food insecurity; (3) observing altered functioning across the brain-gut-microbiome axis; (4) providing early evidence for UPF withdrawal; and (5) elucidating poorer weight management outcomes among persons with UPF addiction. The breadth of recent work on UPF addiction illustrates continued scientific and public interest in the construct and its implications for understanding and treating overeating behaviors and obesity. One pressing gap is the lack of targeted interventions for UPF addiction, which may result in more optimal clinical outcomes for this underserved population.

Aim of the study: The prevalence of childhood and adolescent obesity has risen dramatically over recent decades, particularly in rapidly developing countries undergoing significant dietary transition. Qatar now has one of the highest rates of childhood overweight and obesity globally, coinciding with increased availability and consumption of processed and ultra-processed foods (UPFs).

Results: Evidence consistently demonstrates that processed and ultra-processed foods promote excessive energy intake through five interconnected mechanisms: high energy density and increasing portion sizes; impaired appetite and satiety regulation; displacement of nutrient-dense whole foods; activation of reward pathways that encourage compulsive eating behaviours; and neurobiological and metabolic adaptations that may reinforce long-term overconsumption. Although much of the available evidence originates from Western populations, similar dietary transitions are occurring across Qatar and the wider Gulf region, suggesting these mechanisms are highly relevant to the local context. However, important limitations remain, including the relative scarcity of longitudinal and intervention studies conducted within Middle Eastern populations. Addressing childhood obesity in Qatar requires interventions that extend beyond calorie reduction to target the broader food environment and dietary quality.