Most studies on ketosis have focused on short-term effects, male athletes, or weight loss. Hereby, we studied the effects of short-term ketosis suppression in healthy women on long-standing ketosis. Ten lean (BMI 20.5 ± 1.4), metabolically healthy, pre-menopausal women (age 32.3 ± 8.9) maintaining nutritional ketosis (NK) for > 1 year (3.9 years ± 2.3) underwent three 21-day phases: nutritional ketosis (NK; P1), suppressed ketosis (SuK; P2), and returned to NK (P3). Adherence to each phase was confirmed with daily capillary D-beta-hydroxybutyrate (BHB) tests (P1 = 1.9 ± 0.7; P2 = 0.1 ± 0.1; and P3 = 1.9 ± 0.6 pmol/L). Ageing biomarkers and anthropometrics were evaluated at the end of each phase. Ketosis suppression significantly increased: insulin, 1.78-fold from 33.60 (± 8.63) to 59.80 (± 14.69) pmol/L (p = 0.0002); IGF1, 1.83-fold from 149.30 (± 32.96) to 273.40 (± 85.66) µg/L (p = 0.0045); glucose, 1.17-fold from 78.6 (± 9.5) to 92.2 (± 10.6) mg/dL (p = 0.0088); respiratory quotient (RQ), 1.09-fold 0.66 (± 0.05) to 0.72 (± 0.06; p = 0.0427); and PAI-1, 13.34 (± 6.85) to 16.69 (± 6.26) ng/mL (p = 0.0428). VEGF, EGF, and monocyte chemotactic protein also significantly increased, indicating a pro-inflammatory shift. Sustained ketosis showed no adverse health effects, and may mitigate hyperinsulinemia without impairing metabolic flexibility in metabolically healthy women.

In the pursuit of longevity and healthspan, we are challenged with first overcoming chronic diseases of ageing: cardiovascular disease, hypertension, cancer, dementias, type 2 diabetes mellitus. These are hyperinsulinaemia diseases presented in different tissue types. Hyperinsulinaemia reduces endogenous antioxidants, via increased consumption and reduced synthesis. Hyperinsulinaemia enforces glucose fuelling, consuming 4 NAD⁺ to produce 2 acetyl moieties; beta-oxidation, ketolysis and acetoacetate consume 2, 1 and 0, respectively. This decreases sirtuin, PARPs and oxidative management capacity, leaving reactive oxygen species to diffuse to the cytosol, upregulating aerobic glycolysis, NF-kB and cell division signalling. Also, oxidising cardiolipin, reducing oxidative phosphorylation (OXPHOS) and apoptosis ability; driving a tumourigenic phenotype. Over time, increasing senescent/pathological cell populations occurs, increasing morbidity and mortality. Beta-hydroxybutyrate, an antioxidant, metabolite and signalling molecule, increases synthesis of antioxidants via preserving NAD⁺ availability and enhancing OXPHOS capacity. Fasting and ketogenic diets increase ketogenesis concurrently decreasing insulin secretion and demand; hyperinsulinaemia inhibits ketogenesis. Lifestyles that maintain lower insulin levels decrease antioxidant catabolism, additionally increasing their synthesis, improving oxidative stress management and mitochondrial function and, subsequently, producing healthier cells. This supports tissue and organ health, leading to a better healthspan, the first challenge that must be overcome in the pursuit of youthful longevity.

Metabolic dysfunctions are among the best documented hallmarks of ageing. Cardiovascular disease, Alzheimer’s disease, cancer, type 2 diabetes mellitus, metabolic-dysfunction-associated steatosis liver disease, and fragility fractures are diseases of hyperinsulinaemia that reduce life and healthspan. We studied the effect of suppressing ketosis in 10 lean (BMI 20.5 kg/m² ± 1.4), metabolically healthy, pre-menopausal women (age 32.3 ± 8.9 years) maintaining nutritional ketosis (NK) for an average of 3.9 years (± 2.3) who underwent three 21-day phases: nutritional ketosis (NK; P1), suppressed ketosis (SuK; P2), and returned to NK (P3). Ketosis suppression significantly increased insulin, 1.83-fold (p = 0.0006); glucose, 1.17-fold (p = 0.0088); homeostasis model assessment for insulin resistance (HOMA-IR), 2.13-fold (p = 0.0008); leptin, 3.35-fold (p = 0.0010); total osteocalcin, 1.63-fold (p = 0.0138); and uncarboxylated osteocalcin, 1.98-fold (p = 0.0417) and significantly decreased beta-hydroxybutyrate, 13.50-fold (p = 0.0012) and glucagon-like peptide-1 (GLP-1), 2.40-fold (p = 0.0209). Sustained NK showed no adverse health effects and may mitigate hyperinsulinemia. All biomarkers returned to basal P1 levels after removing the intervention for SuK, indicating that metabolic flexibility was maintained with long-term euketonaemia.

Background: As the growing global population continues to age, the risk of chronic metabolic diseases, including cardiovascular disease, neurodegenerative disorders, type 2 diabetes mellitus, and fatty liver disease, increases considerably. Driven largely by lifestyle factors and metabolic dysfunction, this escalating health crisis is placing mounting pressure on healthcare systems and contributing to significant economic costs. Insulin resistance and hyperinsulinaemia are major drivers of these disorders, emphasising the need for early detection and intervention. Changes in liver enzymes, such as alanine aminotransferase (ALT) and gamma-glutamyl transferase (GGT), commonly assessed in routine laboratory testing, can serve as biomarkers of early-stage insulin resistance, offering a potentially underutilised window for intervention and disease prevention. Correspondingly, low-carbohydrate ketogenic diets have shown to be effective in reversing insulin resistance, metabolic disease, and liver disease. Objectives: We chose to explore the relationship between suppressing ketosis and changes in liver enzymes in the Ketosis Suppression and Ageing cohort. Methods: Ten lean (BMI 20.5 kg/m² ± 1.4), healthy young women (age 32.3 ± 8.9 years) who habitually followed a ketogenic diet maintaining nutritional ketosis (NK) for an average of 3.9 years (±2.3) were exposed to a higher carbohydrate diet, in line with standard healthy eating guidelines for a 21-day phase and then transitioned back to a ketogenic diet. Results: Carbohydrate challenge and suppression of ketosis increased insulin resistance score HOMA-IR by 2.13-fold (p = 0.0008), GKI by 22.28-fold (p = 0.0024), and liver markers ALT by 1.85-fold (p = 0.0010), GGT, 1.29-fold (p = 0.0087) and the ALT/AST, 1.30-fold (p = 0.0266), reflecting an adverse pattern suggestive of hepatic insulin resistance. Conclusions: These results support the clinical utility of liver markers as early and directional signs of hyperinsulinaemia.

During chronic alcohol misuse, hepatic iron overload occurs, leading to exacerbated oxidative stress and liver injury. The aim was to study formulations encapsulated with the antioxidant curcumin to assess their ability protect against oxidative stress in a model of alcohol-related liver disease (ALD) combined with iron. HepG2 (VL-17A) cells were treated with iron (50 µM) alone or with alcohol (200 to 350 mM) over 72 h and markers of oxidative damage, cell death, and mitochondrial function were assessed. Nanoformulations encapsulating curcumin were also studied. VL-17A cells treated with both ethanol and iron showed significant decreases in cell viability (64%, p < 0.0001) when compared to control, and a 56% decrease (p = 0.0279) when compared to iron-only treatment. Iron-alone treatment caused a 115% increase (p < 0.0001) in ROS at 48 h as well as increases of up to 118% when treated with 200 mM ethanol + 50 μM iron (p < 0.0001), compared to control DMEM. The study found that 10 µM curcumin DSPE-PEG increased cell viability by 17% and 41% when compared to control and iron treatment alone, respectively. Formulations reduced ROS by 36% (p = 0.0015) when compared to iron-alone treatment. In summary, encapsulated curcumin provided antioxidant capacity and reduced oxidative stress, demonstrating the therapeutic potential for curcumin formulations in ALD combined with iron dysregulation.