The International Society of Sports Nutrition (ISSN) has published a position stand regarding diets for body weight reduction, aimed at providing a scientific foundation for practitioners, coaches, and trainees. This review critically analyzes existing literature to inform on the effects of various diet types in generally healthy, physically active, and athletic adults, while also considering relevant clinical research on individuals with overweight or obesity.
This position stand does not cover acute dehydration-based weight cutting, pharmacotherapy, or bariatric surgery. The following points summarize the ISSN’s position:
- Diet Categorization: Diets can be categorized by energy deficit magnitude, linearity of the deficit, and macronutrient composition, tailored to individual preferences and goals.
- Energy Restriction: Very-low-energy diets (<800 kcal/day) and low-energy diets (800-1200 kcal/day) may lead to greater short-term weight loss but do not offer long-term advantages over less aggressive calorie-controlled diets. These aggressive diets may increase lean mass loss, though adequate protein intake and resistance training can help mitigate this risk.
- Intermittent Fasting: Evidence suggests no significant differential effects between intermittent fasting variants and continuous energy restriction on body composition outcomes. However, macronutrient quality is crucial for optimizing metabolic health.
- Meal Frequency: Intra-day meal frequency does not significantly impact body weight and fat reduction. Meal frequency should be individualized, with no strict limits prescribed. For physically active individuals, distributing protein intake across at least three meals may help optimize lean mass retention and performance.
What this study does not show
This position stand does not provide evidence on the long-term effectiveness of specific diets or their impact on health outcomes beyond weight reduction.
Evidence scorecard
- Analytic validity: Established
- Clinical validity: Partial
- Clinical utility: Not established
The evidence is based on a review of existing literature.