Background Rapid weight loss (RWL) followed by rapid weight gain (RWG) is a regular pre-competition routine in combat sports and weightlifting. With the prevalence of these sports exceeding 20% at the 2020 Tokyo Olympics, there are limited data on RWL and RWG practices and their impact on well-being and competitive success in elite-level athletes. Methods A total of 138 elite-level female and male judokas, 7.7% of the athletes ranked as top 150 on the International Judo Federation Senior World Ranking List (WRL), completed a survey on RWL, RWG, and the consequences of these practices. Results Our findings showed that 96% of the respondents practice RWL. The average reduced body mass percentage was 5.8 ± 2.3%. Respondents who used either of the dehydration methods – fluid restriction, sauna suit, and/or sauna/hot bath – to reduce weight were 88%, 85%, and 76%, respectively. Furthermore, 91% of the respondents reported reduced energy as a negative consequence of RWL and 21% experienced a collapse episode during the RWL period. Respondents ranked 1–20 on the WRL experienced fewer negative consequences of RWL and RWG ( p = 0.002) and had more dietitian and/or medical doctor support ( p = 0.040) than lower-ranked respondents. Those who started with RWL practices before the age of 16 (38%) were ranked lower on the WRL ( p = 0.004) and reported more negative consequences of RWL and RWG ( p = 0.014). Conclusions This study is the first to provide insight into the RWL practices of worldwide elite-level judokas and provides valuable information for the combat sports society, especially coaches. Proper weight management and optimal timed initiation of RWL practices in a judoka’s career may contribute to success at the elite level.