Background/Objectives: It is unknown whether the negative health effects associated with ultra-processed foods (UPFs) are due to their nutritional composition or to the extent of food processing itself. We evaluated the impact of a test meal composed only of UPF, according to the NOVA classification, compared to a similar meal without UPF in adults with obesity. Methods: This is a parallel, randomized trial. Adult individuals with obesity, according to BMI, % body fat, and/or waist circumference were included. Individuals ate one out of two test meals, matched for energy density, macronutrients, sodium, and fiber, differing in NOVA classification, as a breakfast after a 12-h fast. The rate of intake, appetite, satiety hormones, energy expenditure, and autonomic function were measured. Data were analyzed using mixed analysis of variance. Results: Forty-two individuals were included. We found a significantly faster intake rate (07:52 ± 3:00 vs. 11:07 ± 03:16 min), with less chewing and bites, and greater capacity to eat (39.68 ± 22.69 vs. 23.95 ± 18.92 mm) after the UPF meal, without observed differences in the metabolic outcomes. In an exploratory analysis, after adjusting by sex, leptin levels showed a greater decrease after the test meal in the control group. Conclusions: Although we found a faster intake rate in the UPF meal, only marginal effects were found on the participants’ capacity to eat after the UPF meal. The high similarity between meals, despite differences according to the NOVA classification, may explain these results. As our study was small, these findings require further investigation.

Evidence suggests that the intake of ultra-processed foods (UPF) influences gut microbiota. The present study evaluated the impact of energy restriction of dietary UPF compared to a general energy restriction on the gut microbiota of individuals with obesity. This was a parallel, randomized clinical trial. Individuals with obesity were randomly allocated into two groups: control, with general energy restriction (ER-G), and intervention, with energy restriction associated with UPF restriction (ER-UPF), limited to 5% of total intake. Individuals were followed-up monthly for 6 months. Stool samples were collected at baseline and after 6 months for DNA extraction and sequencing of the 16S rRNA gene (V3–V4 region). Socioeconomic, clinical, anthropometric, and dietary intake data were also collected. Abundance of microbiota data was analyzed using the Linear Models for Microarray Data (limma-voom) and the Microbiome Multivariable Associations with Linear Models (MaAsLin2) packages, with the Benjamini–Hochberg correction method. Alpha-diversity was analyzed using the Shannon, Simpson and Simpson-inverse index, whereas beta-diversity was analyzed using the Bray–Curtis index with the PERMANOVA test. Other variables were analyzed using mixed ANOVA with an alpha level of 5%. A total of 43 individuals were included, and at the end of the study, 34 individuals (18 intervention and 16 control) had complete data and were analyzed. %UPF consumption significantly decreased in the group that restricted UPF (p-interaction = 0.01), whereas waist circumference and body fat decreased in both groups (p-moment < 0.01). It was observed an increase in phylum and family microbial alpha-diversity in both groups with a slight decrease at the genus level. The Ruminococcaceae family showed a significantly greater increase in the ER-UPF group compared to the control group (p-interaction = 0.03), as did the Faecalibacterium genus (p = 0.02). These findings highlight the complexity of interactions between diet, body composition, and gut microbiota, suggesting that UPF restriction may have positive but limited effects on microbiota modulation in the short to medium term. Registration number of Clinical Trial: RBR – 3q9vgk9.

Context: The thermic effect of food (TEF) may be a therapeutic target for the prevention and treatment of obesity. Objective: The impact of different biological and nutritional characteristics on TEF in humans was analyzed. Data Sources: The MEDLINE/PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, and Latin American and Caribbean Health Sciences Literature databases were searched until November 2023 without language restrictions. Data Extraction: Clinical trials were included that offered an oral test meal to adult and elderly individuals in a fasting state and measured TEF using calorimetry. The average TEF of each group was the outcome, and the impact of the individuals' and meal characteristics on the TEF was assessed using subgroups, meta-regression, and compositional analysis. Data Analysis: The review included 133 studies, with 321 different groups. The mean TEF at 60 minutes after the test meal was 262 (95% CI, 236-288) kcal/d and decreased over time until 240 minutes after the test meal (P < .01). Male participants, individuals with normal body mass index, meals with energy content offered according to individual requirements, and meals with a mixed degree of food processing yielded a higher TEF. The total energy content of meals was the variable most strongly associated with TEF. Compositional analysis showed that the amount of lipids in meals was the only macronutrient consistently and negatively associated with TEF. Conclusions: The TEF is influenced by specific individuals’ and meal characteristics. Total energy content and the amount of lipids were the characteristics of the meals most consistently associated with TEF. However, due to important methodological differences between studies, it is difficult to determine how to use TEF as a potential therapeutic target against obesity. Systematic Review Registration: PROSPERO registration no. CRD42023432504.

Background/Objectives: A faster eating rate is associated with increased energy intake and risk of obesity. High consumption of ultra-processed foods (UPFs) is associated with a faster eating rate. Psychobehavioral aspects, such as body image self-perception, eating disorders, and anxiety, may modulate this eating behavior. Therefore, this study examined the moderating role of psychobehavioral factors in the association between meal type (UPF vs non-UPF) and eating rate among individuals with obesity. Methods: It is a secondary analysis of a randomized, parallel clinical trial conducted with 39 adults who have obesity. Participants were assigned to consume either a UPF-only composed meal or a UPF-free meal, both of which were isoenergetic (~550 kcal). Psychobehavioral variables (food addiction—mYFAS 2.0, body image perception and satisfaction—Silhouette Rating Scale, eating disorders—EAT-26, and anxiety—GAD-7) were assessed. Eating rate was measured in kcal/min. Results: Body image perception and satisfaction significantly interacted with the type of meal. In the UPF group, lower body image dissatisfaction was associated with a higher eating rate (β = 4.79 kcal/min; 95% CI: 1.40; 8.19; p = 0.007), while a higher body image perception score was associated with a lower eating rate (β = −4.61 kcal/min; 95% CI: −8.57; −0.65; p = 0.024). No significant associations were observed for food addiction scores, eating disorders or anxiety. Conclusions: Body image modulates the eating rate in the context of UPF consumption. These findings suggest that interventions against obesity should consider individual psychobehavioral characteristics.

Background/Objectives: To evaluate the metabolic and hormonal responses after meals rich in and free of ultra-processed foods (UPF), with high or low energy density (ED), in adults without obesity (body mass index [BMI] between 18.5 and 29.9 kg/m², body fat percentage ≤ 30% for men and ≤42% for women). Methods: Randomized, crossover-controlled feeding trial. Participants were assigned to four conditions (UPF+/ED+, UPF+/ED−, UPF−/ED+, and UPF−/ED−), each receiving two standardized test meals (breakfast and lunch), matched for energy, macronutrients, fiber, saturated fat, free sugar, and sodium. Blood samples were collected after 12 h fasting, and 240 min after each meal completion for quantification of glucose, insulin, triglycerides, ghrelin, and leptin. Results: Nineteen participants (9 females; 22 y mean age; 23.5 kg/m² mean BMI) were included. The UPF condition resulted in a statistically significant increase in postprandial circulating insulin concentrations throughout the day (p = 0.016), without interactions with meal (p = 0.09). No main effects of ED or UPF × ED interactions were observed for any outcome. Conclusions: In this exploratory secondary analysis of a randomized crossover trial, acute UPF consumption resulted in higher postprandial circulating insulin concentrations, independently of ED. These findings require confirmation in adequately powered studies. Brazilian Registry of Clinical Trials (ReBEC), registration number RBR-10gfr3fb.