Issue 221
September 2025
Ray Klerck takes readers past the tale of the tape and into the kitchen, where the real secrets of fight-night style are cooked up.
Fight week can resemble an audition for a famine documentary, while fight night looks like an audition for the role of the prized Turkey in a Thanksgiving ad. While a viral spinning elbow might seem like the ultimate flex, how much water weight, salt, and food you can force-feed into your body after the weigh-ins is fast becoming the double biceps pose. However, two box-fresh studies just gate-crashed that myth, showing that what you stuff back into after the weigh-in doesn’t decide if you win, but it may impact how you fight. The best part about these findings is that they examined things from different perspectives, which makes the buffet bloat a science experiment that a fighter shouldn’t ignore.
THE KO BUFFET
Some fighters step off the scales looking like a raisin in an RVCA hoodie, then 24 hours later, they’ve ballooned into the full fruit basket. Did this overnight trick matter? Well, one group of researchers pulled apart the mechanics behind 308 pro bouts under the California State Athletic Commission’s clipboard gaze. To do this, they split the fighters into regain squads. These included the minimal munchers who barely bounced back (<3%), the middle feeders refuelers, and the full-blown buffet raiders who packed on more than 12%. Those who gained the most weight were more likely to end fights with KOs and TKOs, while the lighter topper-uppers were more likely to drag things in front of the judges for a decision. The weird part was that the amount regained had almost no bearing on who won the bout. So, how much weight a fighter put on after the weigh-in was more likely to dictate the vibe and style of the fight, but not whether or not they got the W. This means the big boys are more likely to come out swinging harder, but that didn’t mean the score cards or a fighter’s chin were going to cooperate.
A differently numerically orientated group of stat-monkeys took a swing at the same piñata and looked at 245 pro MMA fighters between 2018 and 2023. Instead of sorting them into regain squads, they checked whether simple body statistics, such as age, height, and weight, were linked to how much fighters actually regained after the weigh-in. Predictably, the taller fighters regained more weight, fought heavier, and showed up with more meat on their middles. The eyebrow raiser in the mix was the correlation between size and rebound because the bigger the fighter, the smaller the percentage they regained. Conversely, it was the smaller fighters (based on the metrics listed above) who were more likely to deplete their energy on weigh-in day and then blew back up for the fight. This statistical wrinkle shows it’s not just what you put back on, but who you are when you do it.
SCIENCE VS SCIENCE
This is the first time we’ve seen a journal play Mick Maynard because both of these papers appeared in the Journal of the International Society of Sport Nutrition in August 2025. It kind of makes it feel like less of a peer review and more like a title eliminator between rival labs. One camp crunched data on 308 fights and concluded that weight regain shapes the style of fight, with the big hitter swinging for the KOs while the lighter rebounders coast for the decision. The other sliced up the info on 245 fighters and found that smaller athletes rebound in weight more aggressively than their heavier opponents in their classes. Same journal. Same month. Two unique camera angles. The science threw hands, and the takeaway message is a firm draw because they both tell you that a big appetite doesn’t guarantee the W. However, it may have an impact on whether you’re built for the brawl or the final bell.
UNDERLYING FACTORS
To gain a better understanding of why this happens, let’s take a closer look under the hood to get the 101 on glucose. This is the simple sugar your body pulls from food so that it shows up quick-smart in your bloodstream after you eat. When it seesaws up and down, it doesn’t just change your body chemistry; it switches things up in your brain and the resulting MMA performance indicators, as per the above research. There’s growing evidence that links unstable glucose to mood swings, irritability, anxiety, and even bursts of anger. Big blood sugar highs often ride with sadness, while the lows fire up nervousness and agitation. Anyone who has crashed after binging on their favorite refined carbs knows how the rise and fall can twist your headspace. Smart fight nutritionists know this, so they refuel their athletes the smart way to minimize big ebbs and flows. However, this post-weigh-in research takes a more macro approach to the underlying mindsets that may be at play as a result of limiting calories rather than having an abundance, where wild swings create wild arm swings. While keeping things more level may help fighters stick to the long-term game plan.
HUNGER MAD
And the science gets stranger when you zoom in on behavior. To illustrate this, a PNAS study showed that when glucose runs low, people get nastier. You may not believe it, but it made people stab voodoo dolls of their spouses and argue with them more because they didn’t have the blood sugar to keep their temper in check. That kind of reckless aggression makes sense if you’re starving, but the fight data tells a different story. The small rebounders weren’t bezerkers, they were steady and calculated. They seemed able to avoid the sugar rollercoaster altogether, which may be why they dragged more fights to decisions. The big rebounders, on the other hand, spiked their glucose like a Six Flags rollercoaster. They came out aggressive and dangerous, but risked a crash once the rounds stacked up. Together, it shows that unstable glucose, whether too low or too high, may interfere with a fighter’s ability to maintain control. Fighters who keep their glucose level are the ones who can stick to the game plan when it matters.
A SALT SURGE
Glucose isn’t the only rebound chemical shaping a fighter’s psychology. In the lead-up to a weigh-in, most fighters will strip salt from their diets to deliberately wring out every drop of water weight. Their salt levels often increase drastically in the 24-hour reload, typically in the form of electrolytes. While this undoubtedly helps with fluid balance, research on other mammals suggests it may also cause psychological changes. A study in Frontiers in Behavioral Neuroscience found that high salt intake lowered behavioral inhibition and even increased stress hormones like corticosterone, making animals more impulsive and socially bold. Curiously, there are no studies of this nature on humans, but it’s not too far-fetched to believe this may impact fighters, at least to a certain degree. It also tracks neatly with the rebound data, where the bigger the post-weight-in refuel, the more likely the fight will swing toward early aggression and KO attempts. The steady refuelers, who most likely experienced huge electrolyte and glucose spikes, dragged out bouts so they ended on the scorecards. Salt, it seems, may not decide who wins, but may impact how they choose to fight.
THE TAKEAWAY
The real headline is that weight regain isn’t good or bad. That’s kind of the news nobody wants to read, but if you were a betting man, this could help guide where you place your chips. When a fighter loads up big on salt and calories after weigh-in, it will never increase the odds of a win, but it will most likely be a guiding force behind a unique approach to the fight that some may consider high-risk. Keeping the rebound modest won’t lock in victory either. However, it’s more likely to help stay steady and tactical for the long haul. If you’re a fighter, the smart move is knowing which camp your body naturally falls into, then training accordingly. If you’re a big rebounder, prepare to finish early and manage your gas tank with discipline. If you’re a smaller rebounder, hone your pacing and point-scoring tools to survive and thrive in decisions. And across the board, always aim to keep your salt and glucose stable. Spread out your meals, eat natural foods, and avoid cheap sugar rollercoasters. This will help you make sure that your head matches your body when it’s go time.
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