Ketogenic Diet in Obesity and Diabetes: A Narrative Review.

A ketogenic diet (KD) is a low-carbohydrate, high-fat dietary approach. Beyond treating neurologic disorders, KDs have attracted significant media attention for their potential to improve obesity and diabetes. The diet induces a metabolic shift from glucose toward fatty acid oxidation and ketone body production. This shift leads to ketosis, which may reduce hunger, partly through the anorexigenic effects of ketone bodies, thereby contributing to weight loss and improved metabolic parameters, including glycaemic control and insulin sensitivity. In particular, the positive effects of KDs lower insulin demand and may thereby improve β-cell function. However, the long-term efficacy, safety, and sustainability of KDs, especially for diabetes, remain debated. This review offers current insights into the effects of ketogenesis and ketosis, as well as the potential mechanisms underlying them. We explore the metabolic effects of KDs in obesity and diabetes, drawing on preclinical and clinical studies, and suggest that combining KDs with antidiabetic agents may provide synergistic benefits. However, combining KDs with these pharmacotherapies, particularly SGLT-2 inhibitors, requires careful clinical supervision because of potential risks, including euglycaemic diabetic ketoacidosis. We explore how a KD alters the composition of the gut microbiota, thereby affecting host health. We conclude by highlighting challenges and future directions for optimising KD-based therapies and by outlining the limitations of the current review.