Prediabetes and type 2 diabetes mellitus (T2DM) affect 60% of adults in the United States (Centers for Disease Control and Prevention, 2024). Ketogenic diet interventions demonstrate benefit for glycemic management among people with diabetes. The carnivore diet (CD) is a ketogenic diet characterized by exclusive consumption of animal-sourced foods and has not been systematically evaluated. The purpose of this study was to evaluate the direction and magnitude of within-subject changes in glycated hemoglobin (HbA1c) following adoption of a CD and to assess feasibility of recruitment, data collection procedures, and measurement approaches.

An experimental pilot design using a within-subject pre-post analysis was conducted. Adults with HbA1c levels of 5.7% or greater who adhered to a carnivore diet for at least 6 months were recruited through online carnivore communities and social media. Previously collected pre- and post-CD HbA1c values were utilized to evaluate glycemic outcomes. Participants completed a digital survey to self-report health history, diabetes management and medication use, and perceived changes in health status. A carnivore diet-specific food-frequency questionnaire was used to assess dietary adherence and characterize intake patterns. HbA1c was analyzed using paired-samples t tests, while descriptive statistics were used to summarize secondary and feasibility outcomes.

Final analysis included 12 participants. The mean difference in HbA1c decreased 1.47% (SD ± 2.44) p = 0.061, 95% CI (–0.08–3.01). Improvement in HbA1c was reported in 11 people, 41.7% of participants achieved a normal level HbA1c, and 71% discontinued use of diabetes medications during the intervention time frame. Daily red meat intake was reported by 75% of participants.

The findings suggest an association between adopting a carnivore diet and improved glycemic management among adults with prediabetes or T2DM. Sample size and self-reported data limit generalizability and clinical interpretation. Observed changes in HbA1c provide preliminary foundational evidence warranting future prospective investigations evaluating the therapeutic potential of the carnivore diet.

Langlois, Courtney E. "The Carnivore Diet as a Nutritional Intervention for Glycemic Management in Adults With Prediabetes and Type 2 Diabetes." PhD diss., Saybrook University, 2026.

https://www.proquest.com/openview/d29cae668094aa4b36923a433bc9b89c

Highlights

•The heart can metabolize fructose, albeit less effectively than glucose.

•Cardiac fructose metabolism primarily generates glycerate.

•Diabetic hearts show early and marked increases in fructose levels.

•Fructose elevation appears before cardiac dysfunction in diabetes.

Abstract

Increased cardiac risk in diabetes has been linked to disturbances in myocardial metabolism. Circulating and cardiac fructose levels are elevated in diabetes but the relationship between fructose and cardiac pathology is unclear. The goal of this study was to assess myocardial capacity for fructose metabolism and evaluate the time-course of cardiac fructose accumulation relative to the emergence of cardiac functional impairment in diabetic rats. Cardiac capability for fructose metabolism to support function was demonstrated in ex vivo working mouse hearts perfused with 11 mM fructose. Using isotope-labeled fructose [U^(13)C], we observed ^(13)C enrichment into downstream metabolites glyceraldehyde, glycerate, pyruvate, lactate, and mitochondrial acetyl-CoA in perfused working mouse hearts. Metabolite profiling demonstrated that relative to glucose, myocardial fructose metabolism favored glycerate production. In diabetic rats (streptozotocin, 55 mg/kg), cardiac fructose elevation was evident prior to the onset of cardiac dysfunction. This study provides proof-of-principle evidence that fructose metabolism is operational in the working heart and identifies key fructose-derived metabolites. The finding that cardiac fructose elevation precedes functional impairment supports the contention that fructose may be an early instigator of diabetic cardiomyopathy and further investigation is now warranted.

New and Noteworthy (<75 words)

Circulating and cardiac fructose levels are elevated in diabetes but the relationship between fructose and cardiac pathology is unclear. This study provides proof-of-principle evidence that fructose metabolism is operational in the working heart and identifies that cardiac fructose metabolism favors production of glycerate. In diabetes, cardiac fructose elevation precedes functional impairment supporting the contention that fructose may be an early instigator of diabetic cardiomyopathy.

Abstract

Background

Glioblastoma (GBM), isocitrate dehydrogenase (IDH)-wildtype, has a median overall survival of 11-14 months despite standard treatment. Ketogenic metabolic interventions that lower the glucose ketone index (GKI) may improve outcomes. We evaluated the feasibility, tolerability, and potential clinical benefit of integrating standard treatment with an intensive multimodal metabolic therapy program (MTP) in newly diagnosed IDH-wildtype GBM.

Methods

Patients received standard chemoradiation and adjuvant chemotherapy alongside an MTP comprising prolonged fasting, time-restricted feeding, and a ketogenic diet. The primary outcome was the proportion sustaining a mean daily GKI ≤6 during chemoradiation. Secondary outcomes included GKI control throughout chemotherapy, body weight, body mass index, adverse events, performance, exercise, quality of life, and survival, compared with contemporary controls using unadjusted hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

Among 32 eligible patients, 18 commenced chemoradiation with the MTP (intention-to-treat), and 15 completed it (per-protocol). In the intention-to-treat population, 15 of 18 patients (83%) sustained a mean daily GKI ≤6 during chemoradiation. Among per-protocol patients, the GKI was 1.88 ± 0.56 during chemoradiation and 2.53 ± 0.86 throughout chemotherapy. Intentional weight loss averaged 17%, normalizing body mass index. MTP-related adverse events were mild or moderate. Exercise activity and quality of life improved. Median overall survival was 21.5 months versus 14.7 months in controls (HR = 0.42, 95% CI 0.18-0.97, P = .027), with 3-year survival of 27% versus 7%.

Conclusions

Intensive multimodal metabolic therapy was feasible, well-tolerated, and associated with improved exercise activity, quality of life, and survival outcomes, including higher 3-year survival.

Abstract

Obesity represents a major global public health challenge, particularly among women, and is associated with adverse metabolic and endocrine outcomes. his study evaluated the effects of ketogenic, intermittent fasting (IF), and semi-vegetarian diets, alone or combined with home-based exercise, on anthropometric, metabolic, and hormonal parameters in women with obesity. The study employed a pretest–posttest controlled experimental design with 108 women aged 19–45 years, comprising 96 participants with obesity and 12 with normal body weight. Participants were assigned to nine groups: control (C), obese (O), obese with exercise (OE), obese with exercise plus semi-vegetarian diet (OEVD), obese with semi-vegetarian diet (OVD), obese with exercise plus intermittent fasting (OEIF), obese with intermittent fasting (OIF), obese with exercise plus ketogenic diet (OEKD), and obese with ketogenic diet (OKD). Participants completed ketogenic, intermittent fasting (IF), or semi-vegetarian dietary interventions, either alone or combined with home-based exercise, for 6 weeks. Anthropometric parameters were assessed using bioelectrical impedance analysis, while biochemical markers (adiponectin, insulin-like growth factor 1 (IGF-1), irisin, myostatin, glucose, and insulin) were analyzed via ELISA. Statistical analyses were performed using mixed-design ANOVA, Pearson’s correlation, and principal component analysis. The C and O groups exhibited no significant changes, whereas intervention groups showed reductions in body mass, body mass index (BMI), and body fat (p < 0.001). Single interventions were associated with changes in anthropometric measures (OIF:10.42% body mass,7.61% BMI, 9.86% body fat; OE: 9.49%, 6.65%, 13.49%; OVD: 9.07%, 8.17%, 6.21%; OKD: 8.12%, 6.91%, 9.78%). Diet-plus-exercise intervention groups generally exhibited larger changes, with OEVD achieving the greatest reductions (12.69, 13.46, 13.95%), followed by OEKD (10.68, 9.16, 11.17%) and OEIF (8.76, 9.64, 12.04%). Moreover, adiponectin, irisin, IGF-1, and myostatin levels changed significantly in exercise-only and diet-plus-exercise groups compared with those of the C and O groups. Additionally, intervention groups exhibited significant alterations in glucose and insulin concentrations, whereas no significant changes were observed in the C and O groups. Lifestyle modifications integrating dietary strategies with home-based exercise are associated with changes in metabolic and hormonal parameters in women with obesity.

https://www.nature.com/articles/s41598-026-65060-z_reference.pdf

Çınar, Fidan, Fatih Mehmet Uğurlu, Vedat Çınar, Taner Akbulut, Yavuz Yasul, Salih Öner, Elif Subaşı et al. "Metabolic responses of diet–exercise combinations in women with obesity: a comparative lifestyle intervention study with different diet types." Scientific Reports (2026).