Effects of Intermittent Fasting on Hormonal Levels and Physical Performance in Athletes: A Systematic Review
DOI:
https://doi.org/10.55892/jrg.v9i20.3370Keywords:
Intermittent fasting, Physical performance, Hormonal regulation, Athletes, Sports nutritionAbstract
Introduction: Intermittent fasting (IF) has been widely adopted by athletes due to its potential metabolic benefits, including optimization of body composition and modulation of hormonal regulation. However, the effects of this nutritional strategy on physical performance and hormonal responses remain inconclusive in the scientific literature. Studies have demonstrated that IF may modulate hormonal pathways and cellular signaling mechanisms related to exercise adaptation, influencing hormones such as insulin, cortisol, testosterone, and growth hormone. Therefore, understanding the relationship between intermittent fasting, hormonal levels, and athletic performance is essential to provide scientific evidence regarding its applicability in athletes. Objective: To analyze and discuss the effects of intermittent fasting on hormonal levels and physical performance in athletes, considering aspects related to strength, endurance, muscle recovery, and training adaptation. Methodology: This study consisted of a systematic review conducted according to PRISMA guidelines. Searches were performed in the electronic databases PubMed, Medline, Scopus, and Virtual Health Library (VHL), using the descriptors “Intermittent Fasting”, “Hormonal Regulation”, “Physical Performance”, “Insulin Sensitivity”, “Cortisol Levels”, “Muscle Recovery”, and “Exercise Adaptation”, combined using the Boolean operators “AND” and “OR”. Clinical trials, experimental studies, and randomized studies published between 2010 and 2026 investigating the effects of intermittent fasting in athletes and physically active individuals were included. Results and Discussion: The analyzed studies demonstrated that intermittent fasting exerted significant influence on hormonal parameters, body composition, and physical performance. Improvements in insulin sensitivity, reduction in body fat, and modulation of cortisol, testosterone, and growth hormone levels were observed, with variable effects on strength, endurance, and muscle recovery. Furthermore, the effects of IF depended on the adopted fasting protocol, sports modality, training intensity, and nutritional adequacy. Aerobic modalities demonstrated benefits related to metabolic flexibility and endurance, whereas high-intensity exercises presented more heterogeneous results. Conclusion: Intermittent fasting showed potential as a nutritional strategy for athletes, especially regarding improvements in body composition and metabolic parameters. However, its effects on physical performance and hormonal regulation appeared to depend on specific physiological and sports-related factors, highlighting the need for individualized nutritional strategies and further long-term clinical studies.
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