Rapid weight loss (RWL) is commonly practiced among judo athletes. Although it helps them to gain the advantage over their lighter opponents, previous studies have shown that RWL can have a negative impact on the athlete’s performance and overall well-being. This systematic review aimed to synthesize the evidence that examines the influence of rapid weight loss on physiological parameters, biomarkers, and psychological well-being in judo athletes. We followed the preferred reporting items for systematic reviews and meta-analyses guidelines. We searched for studies on Web of Science and PubMed that elaborate on the influence of ≥5% RWL achieved over ≤7-day period in judokas. Out of 52 studies initially found, 14 studies met our eligibility criteria and were included in the review. In total, we examined data from 1103 judo athletes. Retrieved studies showed conflicting data concerning physiological parameters and biomarkers, while psychological well-being parameters were more consistent than physiological and biomarkers. The feeling of tension, anger, and fatigue significantly increased while a decrease in vigor was demonstrated among athletes who lost weight rapidly. The evidence on the impact of RWL on performance remains ambiguous. More studies under standardized conditions are needed in order to provide firm evidence. Considering the harmful effects of RWL outlined in the existing literature, it is important to determine and monitor athlete’s minimal competitive weight to prioritize the health and safety of the athlete, emphasize fairness, and ultimately benefit the sport. View Full-Text