Defining a Ketone Threshold for Weight Loss: Evidence from 14-Day β-Hydroxybutyrate Monitoring

The ketogenic diet is a widely used nutritional intervention for weight loss. The beneficial effects of the ketogenic diet are intrinsically linked to the state of physiological ketosis, where ketone bodies rise, even though the minimal effective threshold of blood ketone concentration that correlates with significant weight loss remains unclear. Therefore, the main purpose of this study was to identify the optimal β-hydroxybutyrate threshold associated with weight loss in individuals with overweight or obesity undergoing a ketogenic diet. This secondary analysis included 217 participants, consisting of 111 males and 106 females, who followed a ketogenic diet for 14 days. Time to Ketosis was calculated for each threshold. Regression analysis showed that a β-hydroxybutyrate concentration of ≥0.5 mmol/L was most associated with significant weight loss. Moreover, body weight and gender significantly influenced Time to Ketosis, suggesting interindividual variability in achieving effective ketosis. Achieving and maintaining a ketonemia of at least 0.5 mmol/L may represent a clinically meaningful threshold to optimize weight loss in individuals undergoing a ketogenic diet. Monitoring β-hydroxybutyrate levels and reducing Time to Ketosis may improve individual responsiveness to ketogenic diet-based interventions.