The Low-Carb Versus Low-Fat Debate: ACritical Path to Precision Nutrition

Abstract

Global obesity and its associated chronic diseases have made low-carbohydrate diets (LCD) and low-fat diets (LFD) mainstream weight-loss strategies, yet their effectiveness and safety remain controversial, with significant methodological limitations in existing research. This paper systematically examines the core controversies surrounding LCD and LFD, focusing on inconsistent definitions, trade-offs between short-term and long-term weight loss, population heterogeneity, disease-specific applicability, and methodological flaws. The study results show that ambiguous definitions—such as varying standards for LCD (e.g., ≤45% of total calories from carbohydrates versus ≤20g/day of carbohydrates)—undermine the comparability across studies. LCD exhibits advantages in short-term weight loss (≤12 months) but lacks such advantages in the long term (≥2 years), and is associated with potential cardiovascular and nutritional risks. Males derive more benefits from LCD, while females show no significant difference in response between the two diets. LCD better improves symptoms of polycystic ovary syndrome (PCOS) in the short term, whereas LFD provides superior long-term blood glucose stability for type 2 diabetes. Additionally, neglecting food quality—such as distinguishing between healthy and unhealthy fats—distorts conclusions about health outcomes. This paper clarifies controversies in the field, highlights methodological gaps, and guides the shift toward precision nutrition, supporting evidence-based dietary recommendations for weight management and chronic disease prevention.