Background/Objectives: The ketogenic diet (KD) is a dietary model that can impact metabolic health and microbiota and has been widely discussed in recent years. This study aimed to evaluate the effects of a 6-week KD on biochemical parameters, gut microbiota, and fecal short-chain fatty acids (SCFAs) in women with overweight/obesity. Methods: Overall, 15 women aged 26–46 years were included in this study. Blood samples, fecal samples, and anthropometric measurements were evaluated at the beginning and end of this study. Results: After KD, the mean body mass index decreased from 29.81 ± 4.74 to 27.12 ± 4.23 kg/m², and all decreases in anthropometric measurements were significant (p < 0.05). Fasting glucose, insulin, homeostasis model assessment of insulin resistance, hemoglobin A1C, urea, and creatinine levels decreased, whereas uric acid levels increased (p < 0.05). Furthermore, increased serum zonulin levels were noted (p = 0.001), whereas fecal butyrate, propionate, acetate, and total SCFA levels decreased (p < 0.05). When the changes in microbiota composition were examined, a decrease in beta diversity (p = 0.001) was observed. After the intervention, a statistically significant increase was noted in the Firmicutes/Bacteroidetes ratio (p = 0.001). Although Oscilibacter, Blautia, and Akkermensia relative abundances increased, Prevotella relative abundance and Bifidobacter abundance, which were the dominant genera before the KD, decreased. Moreover, the abundance of some pathogenic genera, including Escherichia, Klebsilella, and Listeria, increased. Conclusions: In healthy individuals, KD may cause significant changes in microbial composition, leading to dysbiosis and long-term adverse outcomes with changes in serum zonulin and fecal SCFA levels.

Brain fog is a condition that is characterized by poor concentration, memory loss, decreased cognitive function, and mental fatigue. Although it is generally known as a long-term COVID-19 symptom, brain fog has also been reported to be caused by many other diseases. Thus, it is necessary to assess this condition in certain populations. This study aimed to evaluate the reliability and validity of the Brain Fog Scale in a Turkish population. We conducted the study in two phases. In a pilot study including 125 participants, we confirmed the suitability of the scale for validity analyses and then conducted exploratory (n = 230) and confirmatory factor analyses (n = 343). The Cronbach’s alpha value of the 23-item Brain Fog Scale was 0.966. In addition, the 23-item and three-factor structure was confirmed as a result of the analyses. These three factors are mental fatigue, impaired cognitive acuity, and confusion. We also found that participants previously diagnosed with COVID-19 had higher brain fog scores. This finding indicates that brain fog is an important condition that can accompany COVID-19. Furthermore, this validated construct has an acceptable fit and is a valid and useful tool for the Turkish population.

Public health authorities are undertaking initiatives aimed at reducing sugar intake because it is linked to detrimental health outcomes. Individuals’ attitudes and intentions toward sugar can be significant factors affecting intake. Therefore, we here aimed to evaluate individuals’ attitudes and intentions toward sugar intake by combining the theory of planned behavior with different frameworks. Accordingly, we developed an online questionnaire and reached 940 participants. We observed that subjective norms (β = −0.140; p < 0.001) and perceived behavioral control (β = −0.138; p < 0.001) as defined in the theory of planned behavior significantly affected attitude. Subsequently, examining the effect of attitude (β = −0.209; p = 0.018) and intention (β = 0.717; p < 0.001) on sugar intake showed that intention had a positive effect, whereas attitude had no significant effect. Mediation analysis showed that attitude influenced sugar intake through intention (β = −0.286; p = 0.001). Furthermore, we determined that components including habits, perceived understanding, perceived nonautonomy, negativity, and apathy can affect attitude toward sugar intake (p < 0.001). Analyzing the effects of sociodemographic factors revealed that sugar intake was lower in individuals with food allergies (p < 0.05). In conclusion, these findings suggest that the theory of planned behavior, when combined with different frameworks, can be effective in predicting sugar intake and individuals’ intentions.

Background/objectives: Overweight and obesity remain major unresolved public health issues. One contributing factor to the increasing prevalence of obesity is the rising consumption of sugar-sweetened beverages (SSBs), which are a key source of added sugars and excess energy in the diet. Therefore, accurate assessment of beverage intake has become increasingly important for both research and public health interventions. This study aimed to evaluate the validity and reliability of the Turkish version of the Beverage Intake Questionnaire-15 (BEVQ-15) in adults. Methods: A total of 141 adults aged 18–65 years who applied to a private nutrition clinic were included. Data were collected at three time points (T1, T2, T3) through face-to-face interviews. At each time point, participants completed the BEVQ-15 and a 3-day food record. Validity and reliability were evaluated using Spearman correlations, intraclass correlation coefficients, Kendall’s W, and Bland–Altman analyses. Results: Spearman correlations between BEVQ-15 and food records ranged from 0.26 to 0.96 across beverage categories, with the majority of categories demonstrating correlations of 0.50 or higher. Test–retest reliability was excellent for water (ICC = 0.94), moderate for diet beverages (ICC = 0.70), and total SSBs (ICC = 0.65). Bland–Altman analysis showed that 87% of beverage categories achieved ≥95% agreement within the limits of agreement. Conclusion: These findings indicate that the Turkish version of the BEVQ-15 is a valid and reliable instrument for assessing beverage consumption among adults.

Background/objectives: Despite increasing global interest in veganism, integrative models that incorporate ethical, environmental, and psychosocial determinants within the Theory of Planned Behavior (TPB) remain limited in Türkiye. This study aimed to extend the TPB by including ethical, environmental, and health-related motivations to better explain individuals’ intentions and behaviors related to adopting and maintaining a vegan diet. Methods: A cross-sectional online survey was conducted among adults in Türkiye who identified with or engaged in veganism. Twelve latent variables were assessed using validated scales, and the extended model was tested through structural equation modeling with additional robustness procedures, including spline adjustments, PCA, Elastic Net regularization, and instrumental variable analyses. Results: Subjective norms and perceived behavioral control significantly predicted vegan intention, with subjective norms emerging as the strongest determinant. Ethical motivation strongly predicted intention but did not directly predict actual adherence. Unexpectedly, environmental and health motivations were negatively associated with adherence. Women reported stronger intentions despite perceiving lower social support. Conclusion: This study broadens the TPB by integrating ethical, normative, and psychosocial dimensions that explain vegan intentions beyond traditional predictors. Findings underscore the importance of moral identity, perceived social expectations, and contextual factors in shaping sustainable dietary behaviors.

Background/Objectives: Dietary interventions are central to irritable bowel syndrome (IBS) management, but evidence directly comparing a low-FODMAP diet (LF), adapted NICE dietary advice (NICE), and adapted NICE dietary advice combined with intermittent fasting (NICE–IF) is limited. This study compared the short-term effects of LF, NICE, and NICE–IF on IBS symptom severity and disease-specific quality of life. Methods: In this prospective, three-arm, non-randomized controlled dietary intervention study, adults with IBS followed LF, NICE, or NICE–IF for two weeks. IBS symptom severity, disease-specific quality of life, and psychological status were assessed using the Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS), the IBS Quality of Life questionnaire (IBS-QOL), and the Hospital Anxiety and Depression Scale (HADS), respectively, at baseline and after the two-week intervention; stool consistency was monitored using the Bristol Stool Form Scale (BSFS). Between-group differences were additionally examined using analysis of covariance (ANCOVA) adjusted for baseline values. Results: Eighty-one participants completed the study. IBS symptom severity decreased significantly in all groups (all p < 0.001), with a significant between-group difference in change (p = 0.018); the reduction was greater with LF than with NICE (p = 0.017). IBS-specific quality of life improved significantly in all groups (all p ≤ 0.002). Although the overall change differed among groups (p = 0.012), pairwise differences were not significant. After adjustment for baseline values, no significant between-group differences remained for symptom severity (p = 0.294) or quality of life (p = 0.333). Post-intervention stool consistency did not differ among groups (p = 0.485). A significant within-group reduction in anxiety scores was observed only in the NICE group (p = 0.025). Conclusions: All three interventions were associated with short-term improvements in IBS symptoms and quality of life. The greater unadjusted reduction in overall symptom severity with LF than with NICE was not robust to adjustment for baseline severity, and no between-group differences in quality-of-life improvement were observed; these findings require confirmation in larger, fully randomized studies with longer follow-up.