Effects of Intermittent Fasting and Calorie Restriction on Exercise Performance: A Systematic Review and...

Area of Science:

• Sports Medicine
• Nutritional Science
• Exercise Physiology

Background:

• Intermittent fasting (IF) and calorie restriction (CR) are popular dietary strategies for weight loss and metabolic health.
• Combining IF/CR with exercise is common for improving body composition and physical performance.
• The impact of IF/CR combined with exercise on physical performance, despite weight loss, requires further investigation.

Purpose of the Study:

• To systematically evaluate the effects of IF and CR, when combined with exercise, on exercise performance and body composition in adults.
• To compare outcomes of IF/CR plus exercise versus exercise alone.

Main Methods:

• Systematic review and meta-analysis of randomized controlled trials (RCTs) up to April 2024.
• Searched PubMed, Web of Science, and Scopus for studies on IF/CR combined with exercise versus exercise alone.
• Analyzed outcomes including VO2max, strength, jump performance, gait speed, body weight, BMI, fat-free mass, fat mass, and body fat percentage.

Main Results:

• IF/CR combined with exercise significantly increased handgrip strength compared to exercise alone.
• No significant effects were observed on VO2max, bench press, knee extensor strength, leg press, countermovement jump, 400m walk test, or gait speed.
• IF/CR combined with exercise significantly decreased body weight, BMI, fat mass, fat-free mass, and body fat percentage.

Conclusions:

• Integrating IF or CR with exercise is effective for weight loss and improving body composition without compromising most physical performance metrics.
• Weight loss induced by IF/CR and exercise does not necessarily lead to reduced physical performance in adults.
• Individual variability in body composition, capacity, diet, and exercise may influence real-world outcomes.