Study – Average MMA Fighter Gains Over 8% Body Mass From Weigh Ins to Fight Time

Rapid Extreme Weight Cutting is a prevalent occurrence in mixed martial arts with many injuries and even deaths tied to the practice.

The practice is employed with fighters either hoping to gain a size advantage over their opponent, or given how common the practice has become, to prevent having a size disadvantage. A recent study was published this month in the International Journal of Sport Nutrition and Exercise Metabolism shedding light on just how common the practice is and how much weight athletes gain following their weigh ins.

In the study, titled Rapid Weight Gain Following Weight Cutting in Male and Female Professional Mixed Martial Artists, the authors reviewed official data from the California State Athletic Commission from 2015-2018. During this period weigh in data and fight day weight data were collected from a total of 512 athletes. The data revealed that on average 8% of total body weight was gained by competition time. Over 25% of men and over 33% of women gained over 10% of body mass by competition time revealing the prevalence of extreme dehydration for making weight. The data also revealed that 98% of athletes gained weight by competition time with only a few heavyweights presumably not doing so. The key takeaway from this data is that an athlete is basically guaranteed to be at a size disadvantage if they don’t engage in rapid weight cut practices which are a documented danger in and of themselves.

The full abstract reads as follows:

Rapid weight loss or “weight cutting” is a common but potentially harmful practice used in mixed martial arts competition. Following the official weigh-in, competitors refeed and rehydrate themselves in a process known as rapid weight gain (RWG) to realize a potential competitive advantage. While data from surveys and small series have indicated the majority of mixed martial arts athletes engage in rapid weight loss, there is a lack of officially collected data from sanctioning organizations describing its prevalence. The present investigation represents a summary of the data collected between December 2015 and January 2018 by the California State Athletic Commission. In total, 512 professional mixed martial artists (455 males and 57 females) were included. Of these, 503 (98%) athletes gained body mass between weigh-in and their bouts. Total RWG between weigh-in and competition was 5.5 ± 2.5 kg, corresponding to an 8.1% ± 3.6% body mass increase. Total RWG was 5.6 ± 2.5 kg (8.1% ± 3.6%) for males and 4.5 ± 2.3 kg (8.0% ± 3.8%) for females. More than one quarter of men and one third of women gained >10% body mass between weigh-in and competition. Athletes from leading international promotions gained more absolute, but not relative, body mass than those from regional promotions. Our findings indicate RWG is nearly ubiquitous in professional , with a similar prevalence in male and female athletes. Trends based on promotion suggest a larger magnitude of RWG in presumably more experienced and/or successful mixed martial artists from leading international promotions.


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