Differential Metabolic Effects of Saturated Versus Polyunsaturated Fats in Ketogenic Diets

Summary

Crossover trial comparing two isocaloric ketogenic diets in healthy adults: one enriched in saturated fat, one enriched in polyunsaturated fat. Both diets supplied roughly 70% of energy as fat with carbohydrate held below 30 grams per day. The authors measured plasma ketones, lipids, and insulin sensitivity across both arms. The headline result for fasting-protocol design: ketogenesis was robust across both fat types — the question is not whether unsaturated fats permit ketosis (they do) but the relative depth of ketosis they produce. The unsaturated-fat arm reached higher β-hydroxybutyrate concentrations than the saturated-fat arm. Insulin sensitivity and lipid markers diverged between arms in ways consistent with the broader saturated-vs-unsaturated literature.