It is a sight well known to fans of all combat sports: A fighter walks onto a stage on a Friday, waving to the cheering crowd before stripping down to their sponsored underwear and stepping onto a weighing scale so an official can check their weight. The fighter waits nervously for a few moments before flexing both biceps to the crowd, celebrating that they’ve qualified for their chosen weight division. They immediately step off the scale, put their tracksuit trousers back on and start to chug from a 1.5-liter bottle of a brightly colored liquid handed to them by a coach. This routine occurs the day prior to every fight card and is designed to make sure both competitors are the same size, theoretically making it a fair contest. Importantly, this is the final—usually the only—time that either fighter’s weight is checked by the organizers, meaning they only need to be “on weight” for the few seconds they are stood on the scale. So, in the weeks leading up to weigh-in, both competitors will engage in weight cutting to be as light as they can be. As soon as their contracted weight is confirmed, the race is on to regain as much weight as possible to try and get a perceived advantage over the other fighter.
MMA fans are well aware that weight cutting takes place, with most viewing it as part of the sport and even essential for success. Many may have done it themselves as competitors in one sport or another. It’s questionable, however, whether people appreciate the consequences weight cutting has for the athlete’s health or performance. The aim of this piece, therefore, is to provide that understanding, so that MMA fans and followers have a better insight into these practices.
Weight cutting generally occurs in three stages: the chronic weight loss stage (CWL) where fighters will restrict their food intake and increase their training over several weeks before the weigh-in; the rapid weight loss stage (RWL) where fighters will engage in extreme dehydration and food restriction in the days immediately before the weigh-in; followed by the rapid weight gain stage (RWG) when the athlete will attempt to rehydrate and refuel to put their weight back on. Though weight cutting is common in all combat sports as well as sports such as horse racing and rowing, MMA fighters not only cut more overall weight (9.8 kg/21.6lbs) than other combat sports (3.8–5.9 kg/8.3 – 13lbs), but they cut more in the 24 hours before weigh-in as well (MMA = 3.4 kg/7.5lbs, other combat sports = 1.4-2.3kg/3-5lbs).
So how do they achieve this? Roughly half of MMA fighters reported missing 1-2 meals per day or fasting the entire day, with another group of fighters being found to eat as little as 300-750 calories per day in the week before a bout. The body requires these calories to perform and recover, with competitive athletes generally needing at least 3,000–5,000 calories per day just to break even. This extreme food restriction puts the athletes in a position called “low energy availability,” where the body does not have enough fuel to complete its basic tasks such as hormone management, organ and muscle recovery or cognitive function.
In terms of dehydration, 76% of MMA fighters reported using saunas, compared to only 36-51% of fighters in other combat sports. Use of sweat suits is also more common in MMA with 63% of fighters using these, with 16-50% use in the other sports. The only combat sport reporting greater use of sweat suits than MMA was wrestling, with 83% of these athletes using this method. Importantly though, as mentioned previously, wrestlers cut less weight than MMA fighters, suggesting less overall dehydration before competition.
Such energy and fluid restriction means there is less glycogen available for the brain to function optimally, and less water in the body’s cell and blood stream. This lack of fluid in the blood makes it thicker and more difficult for the heart to move, meaning 25-30% less blood is pumped on each beat, increasing resting heart rate, increasing the body’s core temperature and reducing the amount of blood being delivered to the working muscles. All of this leads to reduced cognitive and sympathetic nervous system responses, reduced force production and reduced work capacity with increased effort required to complete this work with none of these effects returning to normal within 24 hours. In other words, competitive athletes are entering a contest physiologically unable to perform anywhere close to their maximum capacity. Of more concern, however, is the effect this has on the athlete’s health. In 2018 a team of researchers studied a professional MMA fighter throughout their training camp, tracking their weight loss and physiological responses to the CWL/RWL methods used. Over eight weeks this fighter lost 17kg/37.5lbs while eating 1,300–1,900 calories per day, with 7kg/15.4lbs being lost mostly via dehydration in the 36 hours before weigh-in. This combination of low energy availability and dehydration caused a severe reduction in their testosterone production with a sharp increase in cortisol. This fighter also experienced a large increase in both urea and creatinine in their blood, indicative of kidney malfunction, in addition to an extremely high blood sodium content. Taken together, these findings would give cause to book this particular fighter into a hospital bed, not a professional MMA bout.
Despite these worrying results, this particular fighter made it to the cage to compete. We have, however, seen several fighters collapsing on the scale during the weigh-in itself, with one documented case of a very prominent fighter going blind trying to cut weight. These are by no means isolated incidences either, with one website maintaining an periodically updated list of missed weight cuts, athlete hospitalisations, emergency surgeries and deaths resulting from fighters cutting weight. 43% of athletes at a UK MMA event were found to be severely dehydrated prior to competition with their hydration and weight loss readings similar to those reported in weight cutting fatalities in US collegiate wrestling in the 1990s. Tellingly, it was those tragic events that led to widespread rule and culture changes within wrestling. Thus far in MMA there is at least one fighter fatality formally linked to weight cutting in medical case reports. Outside of the medical literature we can point to the deaths of Leandro Souza from an apparent stroke in 2013 and Yang Jian Bing in 2015 reportedly caused by cardiopulmonary failure. Both were undergoing severe dehydration to make weight for professional bouts. Amateur fighters are also at risk, as evidenced by the 2017 death of 18-year-old muay thai fighter Jessica Lindsay. These were all people just trying to compete in their sports. There also appears to be the potential for long term consequences even if athletes avoid this worst-case scenario. Going through extreme food restriction on such a regular basis has been linked to the onset of eating disorders amongst MMA fighters. On the same note, youth athletes taking part in Olympic combat sports have displayed elevated incidences of eating disorders, and 22% of female athletes not experiencing their menstrual cycle, a strong sign of low energy availability preventing the hormone system from functioning as it should.
So who is assisting fighters in their weight cut? Who is deciding which methods to use and how severe they need to be? Terrifyingly, it is rarely anyone with any kind of medical, dietary or physiological training or education. Advice and guidance is overwhelmingly provided by coaches and training partners. With such extreme consequences, and with so little qualified guidance being sought, it is clear to see why there is such a high incidence of athletes requiring medical treatment from the effects of trying to make weight. The coaches and training partners may know how to get a fighter down to their required weight, but it is clear that most do not know how to do this safely or without reducing their athlete’s performance.
A common response to this information from fans, coaches and fighters alike is “but cutting weight gives a better chance of winning.” This is questionable. There is some evidence that the amount of weight cut and regained is related to winning in grappling only sports such as judo and wrestling. The opposite is found in striking-only sports where no difference between winners and losers can be found. Data from elite MMA competition shows no difference in the amount of weight lost or regained between winners or losers, with most competitors stepping in the cage being one or two divisions heavier than their official weigh-in. Similarly, another research group found that MMA fighters who cut more weight lost their bouts more often than those who cut less weight. In support of this, it has also been shown that fighters who engage in less severe energy restriction during the RWL stage stand more chance of winning. Currently, the only data showing any difference in weight lost or regained between MMA winners and losers is found at the regional levels of the sport. In this particular study, weight gain did not differentiate between winners or losers at the elite level—Ultimate Fighting Championship and Bellator MMA—or the beginner level. Only regional standard fighters (Legacy Fighting Alliance for instance) were positively affected. As such, it seems there is little advantage to be gained from extreme weight cutting. The effect of weight cutting at the regional level may potentially be explained by the skill disparity that often occurs between competitors at this level, meaning one fighter may not be good enough to overcome even a small weight discrepancy.
Based on this evidence, it appears we have a situation where fighters are engaging in practices that prevent optimal performance, puts them at risk of long-term health problems and even death, with this process being led mostly by unqualified people. That fighters are also stepping into the cage one or two divisions heavier than their official weight signals that these athletes are in a race to the bottom. Fighters in most divisions could potentially all move up one weight class and still be facing the exact same opponents, only without sacrificing their performance, health or risking their lives. And let me clear here – weight classes exist for a reason. Everything else considered, the bigger person will most often win a contest; nobody is denying that. What we have in MMA, however, is athletes of essentially the same size cutting essentially the same amount of weight and therefore not gaining any actual advantage.
So what do we do? There are many voices calling for stricter rules, more frequent weigh-ins or hydration checks. Unfortunately, there is sufficient evidence to show that fighters treat these rules as ‘flexible’ or there to be worked around. Any stricter ruling would likely lead to athletes and camps developing more extreme methods to get around them. On top of this, the hydration test used by some promotions does not actually provide any reliable information about how well hydrated the athlete is or isn’t. Instead, what I propose we need is a culture change in our sport to reduce the amount of weight being cut by fighters across the board, and to start making use of safer and more effective methods. These methods include avoiding extreme dehydration and ensuring the athlete consumes enough food to at least meet their energy availability needs. When prescribed by a trained and registered sports nutritionist, these methods have the potential to minimize the most negative consequences of weight cutting while maintaining the physical performance levels needed for successful competition. Coaches and athletes being more actively encouraged by promoters and commissions to move up to a division more in keeping with their actual body size would also bring about more dialogue about moving MMA away from the current extremes.
It is clear at this point that weight cutting as currently practiced in MMA is extreme, leads to short term performance decrements, potentially long-term health problems and has caused the avoidable deaths of several otherwise healthy, young people. Changing this culture requires active and pre-emptive engagement between promoters, governing bodies, legislators, coaches and fighters. With the rapid global growth of amateur MMA bringing athletes into the sport from a younger age, now is the time to develop education and cooperation strategies to reduce extreme weight cutting and promote safer, more effective athlete weight management practices for all involved.
Dr. Christopher Kirk is a sport scientist specializing in the physiological effects of training and competing in MMA. He is a Lecturer of Sport and Exercise Physiology at Sheffield Hallam University (UK) and provides sports science and S&C support to fighters and other athletes through his private practice, Altius Sports Performance. He is also a member of the IMMAF Athlete Weight Management task force. @ChrisKirk_ASP