Rapid weight loss and kidney function


Rapid weight loss (RWL) is commonplace in most combat sports in order to gain a perceived competitive advantage over opponents. Despite this, strong concerns remain regarding the safety for athletes undergoing this process. As the main mechanism of rapid weight loss is dehydration, it makes sense that the kidneys are placed under a significant degree of stress. This systematic review aimed to synthesize the current evidence in relation to the impact of rapid weight loss in combat sports athletes on kidney function.

A total of 10 studies, including 171 athletes from judo, TKD, MMA, muay thai and wrestling were included in the review. Creatinine (Cr) and blood urea nitrogen (BUN) were the most commonly used markers of kidney function, while urine specific gravity (USG) was the most commonly used measure of hydration. 

Whilst care needs to be taken when interpreting dehydration using USG alone, due to some inherent limitations of the measurement, there appears to be a strong correlation between dehydration and acute kidney injury following rapid weight loss. 

Acute kidney injury and chronic kidney disease have been linked, however more longitudinal data is required to ascertain the effect of repeated RWL on chronic kidney function. 

Coaches and athletes should be aware of the risks associated with rapid weight loss and take all necessary precautions to mitigate these deleterious effects.

#rapidweightloss #weightcutting #combatsports #thescienceofstriking #muaythai #taekwondo #wrestling #judo #mma #mixedmartialarts #onefc #ufc #bellator

Lakicevic, N., Paoli, A., Roklicer, R., Trivic, T., Korovljev, D., Ostojic, S. M., … & Drid, P. (2021). Effects of Rapid Weight Loss on Kidney Function in Combat Sport Athletes. Medicina, 57(6), 551.

About the author

Sam Gilbert

Sam Gilbert is a registered physiotherapist with the Australian Physiotherapy Association (APA) and certified strength and conditioning specialist (CSCS) with the National Strength and Conditioning Association (NSCA). He holds a bachelor’s degree in Physiotherapy from Latrobe university (Melbourne, Australia) and a master’s degree in Exercise Science (Strength and Conditioning) from Edith Cowan University (Perth, Australia).

A 3rd Dan black belt in Shinkyokushinkai Karate under the World Karate Organisation (WKO), Sam participated for over 20 years in full contact competition, winning multiple state and national titles, and culminating in a 4th place in the heavyweight division of the Shinkyokushinkai World Cup in 2009.

As the co-founder and clinical director of Club 360, the premier multi-disciplinary health and fitness center in Tokyo, Japan, Sam has combined his practical experience with an in-depth study of sports performance in relation to combat sports, and strives to help other combat athletes reach their full competitive potential, whilst at the same time decreasing injury risk and increasing competition and training potential.

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By Sam Gilbert