Background/Objectives: Ultra-processed foods (UPFs) have become a dominant component of the modern diet, paralleling the rise in obesity and chronic disease prevalence worldwide. This narrative review aims to synthesize evidence on how dietary processing and UPF consumption interacts with dietary quality, energy balance, and biological pathways to influence metabolic health. Methods: We performed a targeted literature search of peer-reviewed articles and authoritative reports examining UPF definition (via the NOVA classification), global consumption patterns, behavioral drivers of overconsumption, nutrient composition, and mechanistic links to metabolic dysfunction. Emphasis was placed on recent human and animal research relating UPFs to obesity, cardiometabolic outcomes, inflammation and gut microbiome alterations. Results: High UPF intake is consistently associated with reduced diet quality (higher saturated fat, sugar, sodium; lower fiber and micronutrients), increased energy density, faster eating rates and activation of reward pathways. These factors facilitate excessive energy intake and adiposity, promoting metabolic dysregulation, chronic low-grade inflammation, hormonal disturbances and gut microbiome shifts. While cross-sectional and cohort evidence is extensive, causal intervention trials and mechanistic human work remain limited. Conclusions: The accumulated evidence suggests that UPFs may influence chronic disease risk through their unbalanced nutrient profiles and through additional effects introduced by industrial processing. To translate these insights into public health strategies, future work should prioritize real-world intervention studies to reduce UPF consumption and examine resulting effects on energy balance, inflammation and gut health.

Background: The prevalence of diabetes increases with age, and food bioactive compounds have shown potential in mitigating its development. This study aimed to evaluate the efficacy of curcumin in preventing type 2 diabetes mellitus (T2DM) in older adults with prediabetes. We hypothesized that curcumin, due to its insulin-sensitizing effects, would help maintain glucose homeostasis, metabolic health, and gut health. Methods: This randomized, double-blind, placebo-controlled trial included 28 older adults (aged 60 years or older) with prediabetes or overweight/obesity. Participants were randomly assigned to receive either curcumin (80 mg) or placebo capsules for 12 weeks. The primary outcome measures were glucose homeostasis markers, including hemoglobin A1c (HbA1c), blood glucose, and insulin levels. Secondary outcomes included body composition, body mass index (BMI), body weight, lipid profiles, and gut microbiome composition. Data normality was assessed using the Shapiro–Wilk test, and two-way repeated-measures ANOVA with multiple comparisons was used to find differences between groups and over time. Results: A total of 23 participants (age = 66.52 ± 5.76 years; 14 in the curcumin group and 9 in the placebo group) completed the 12-week intervention. HbA1c levels significantly decreased in the curcumin group, whereas levels remained stable in the placebo group. While the curcumin group observed an increase in AST levels, the ALT level was reduced in the placebo group. Both the curcumin and placebo groups showed a reduced ALT/AST ratio by the end of the intervention. Body mass index, lipid profiles, and body composition showed no significant changes over the study period. Gut microbiome analysis revealed no significant changes in alpha diversity or beta diversity of microbiome; however, there was marginal enrichment of beneficial bacteria such as Bacteroidota (phylum), Bacteroidaceae (family), Agathobacter, Bacteroides, and Roseburia (genera) in the curcumin-supplemented group over time. Conclusions: Curcumin supplementation improved or favorably maintained glucose homeostasis and showed modest improvements in beneficial gut microbiota in older adults with prediabetes, potentially reducing the risk of developing diabetes. Long-term studies with larger sample sizes are needed to confirm these findings and determine the clinical relevance of curcumin supplementation for prediabetes prevention.

Normal weight obesity (NWO) is a body composition phenotype that is associated with increased cardiometabolic risk and is characterized by a normal weight body mass index but elevated body fat. The purpose of this study was to determine sex differences in aerobic capacity across body composition phenotypes, including normal weight lean (NWL), NWO, and traditional obesity (OB). We recruited 60 participants according to three body composition phenotypes: NWL (n = 10 females, n = 10 males), NWO (n = 10 females, n = 10 males), and OB (n = 10 females, n = 10 males). Measurements included fasting metabolic risk factors, body composition X-ray scan, and peak exercise test on a cycle ergometer to determine aerobic capacity (VO_2peak). Across groups, males (34.5 ± 11.7 mL/kg/min) exhibited greater VO_2peak than females (28.8 ± 8.8 mL/kg/min; p = 0.04). There were no differences in VO_2peak between sexes within the same body composition phenotype, but NWL (42.7 ± 9.0 mL/kg/min) exhibited greater VO_2peak than NWO (27.9 ± 4.4 mL/kg/min; p < 0.0001) and OB (24.4 ± 7.3 mL/kg/min; p < 0.0001). VO_2peak was inversely correlated with relative body fat in the full sample (r = −0.67; p < 0.0001), but was stronger in males (r = −0.78; p < 0.0001) than females (r = −0.53; p = 0.0028). Visceral adipose tissue was not significantly correlated with VO_2peak in the full sample (r = −0.25; p = 0.05) or in males (r = −0.23; p = 0.25), although they were inversely correlated in females (r = −0.36; p = 0.048). Our results suggest low aerobic capacity in both men and women with NWO, similar to men and women with OB. The relationship between body composition and aerobic capacity is strong across body composition phenotypes, but appears to be more consistent in females than males. For healthcare professionals aiming to lower cardiometabolic risk, attention should be given to improving aerobic fitness in both men and women with elevated body fat, including those with NWO.

Background: Despite a long-standing appreciation for the benefits of dietary fiber consumption, there is a lack of interventions focused exclusively on improving dietary fiber intake. Aim: The aim of this study is to determine the effects of an intervention focused singularly on improving dietary fiber on weight, eating behavior, and markers of cardiometabolic risk. Methods: This pilot study will employ a three-arm, factorial design to examine effects of a novel dietary fiber-focused intervention: Fiber for Improvement of Behavior, Eating, and Risk (FIBER), compared to standard weight loss education alone or in combination with FIBER. FIBER is 3 months long, including group-based educational sessions and remote counseling using motivational interviewing. Intervention content is focused on dietary fiber. This includes what dietary fiber is, where to find it, why to consume it, and how to consume it via theory-driven behavior change techniques and strategies (e.g. observational learning). Adults consuming ≤25 g of dietary fiber/day and a body mass index ≥30 kg/m ² will be recruited using online advertisements. Participants will complete in-person data collection visits at baseline and 1 and 2 years post-FIBER to measure body mass (primary outcome), blood lipids, dietary fiber intake, behavior and cognitive measures, stool samples, and body composition (secondary outcomes). One remote data collection session will occur directly after FIBER to assess dietary fiber intake and behavior and cognitive measures. Summary: This study will provide data regarding effects of a dietary fiber-focused intervention on diet and eating-related behavior, body weight, and cardiometabolic risk factors in adults with obesity.

Ultra-processed foods (UPFs) account for a substantial proportion of energy intake and are commonly characterized by being low in protein. The growing availability of protein-fortified UPFs may contribute considerably to dietary protein intake. This study examined associations between UPF consumption and protein intake and evaluated the effects of UPF reduction on protein intake. Fifty-two healthy adults were randomized to either minimize UPF consumption (MPF; n = 25) or maintain typical dietary patterns (UPF; n = 27) for six months. Dietary intake was assessed using three-day diet records at baseline and post-intervention, and foods were classified by the Nova Food Classification System. At baseline, UPF consumption was positively associated with UPF-derived protein intake and the proportion of protein obtained from UPFs (p’s < 0.0001), while demonstrating inverse associations with protein intake relative to body mass and the percentage of calories derived from protein. The MPF group significantly reduced UPF consumption and UPF-derived protein intake (p’s < 0.0001). Despite this, total protein intake, protein intake relative to body mass, and percentage of calories derived from protein were maintained. These findings suggest that dietary protein adequacy can be preserved during UPF reduction while decreasing reliance on UPF-derived protein sources.