Protein Requirements During Very-Low-Calorie Ketogenic Diet for Obesity-Limitations of Ideal Body Weight: An Updated Mini- Review

Abstract

Very-low-energy ketogenic therapy (VLEKT) is widely used in obesity management and commonly prescribes protein intake according to ideal body weight (IBW). Although this approach is practical and widely adopted in current guidelines, IBW does not directly reflect fat-free mass, skeletal muscle reserves, or the marked heterogeneity in body composition observed among individuals with obesity. This narrative mini-review examines the physiological basis of protein prescription during VLEKT and discusses the limitations of IBW-based approaches, with emphasis on sarcopenic obesity, anabolic resistance, preservation of lean mass during rapid weight loss, and body composition assessment. Available evidence indicates that reductions in lean tissue may still occur despite conventional protein prescriptions based on IBW. While no validated model for body-composition-guided protein prescription currently exists, the physiological rationale supporting fat-free-mass-based approaches deserves further investigation.

Keywords: Very-low-energy ketogenic therapy, VLEKT, Very-low-calorie ketogenic diet, VLCKD, Protein requirements, Ideal body weight, Fat-free mass, Body composition, Sarcopenic obesity, Obesity