Science Examines Rehydration After Weight Cutting

According to a recent study , if you are losing a substantial amount of weight when cutting, you may not be fully recovered by the time your fight comes around.

As a coach I became an expert in weight cutting for MMA athletes. I did this because there is a need for it. Some of the practices I’ve witnessed to cut weight are simply ridiculous and often extreme. Fighters are just asking to hurt themselves.

There’s definitely a wrong way to cut weight, and there’s also definitely a better way. However, according to a recent study in the Journal of Strength and Conditioning, if you are losing a substantial amount of weight when cutting, you may not be fully recovered by the time the fight comes around, even with a full day to recover.

In the study, the researchers looked at forty MMA fighters, including a few WMMA participants. The testing was simple. Researchers looked at the athletes’ physical characteristics, like their weights, and took a urine sample to measure dehydration around weigh-in time the day before their fights and then again about two hours before fight time.

The focus of the study was on the weight gained between weigh-in and competition, as well as the competition hydration status. This is a refreshing change over the usual weight cutting study that is only interested in how much weight has been lost initially. This study discovered an average of about 3.4 kg (7.5 lbs) was restored between weigh-in and two hours pre-fight. This amounted to about 4.4% of the fighter’s bodyweight on average.

That much weight gained back doesn’t quite sound like enough compared to how much people typically cut for MMA fights. Sure enough, the researchers found that as of two hours before their fights, 39% of the athletes were still significantly dehydrated, of which 11% were considered seriously dehydrated.

Of course competing in a dehydrated state isn’t the best for your health and probably negatively impacts performance as well. It’s best to avoid this, of course. Putting the weight back on most efficiently and getting back to where you started from would seem like the best option, but the researchers looked into that as well.

In perhaps the most interesting part of the study, the researchers claimed that there was no correlation between changes in body weight and dehydration. They don’t cover this in much depth at all, and it rings false. Perhaps, however, what is meant is that putting the weight back on does not necessarily mean that the athlete has become hydrated.

One potential reason for this finding might be that when the athlete begins eating again the increase in glycogen stores and other nutrients will absorb much of the water consumed during that period. That would contribute to bodyweight but not hydration status. This is speculation, as the researchers don’t mention this at all.

Ultimately, the bottom line is that weight cutting may be a part of the sport, but for health and performance, it’s important to not go overboard. When recovering from the weigh-in, be sure to take in more fluids than you are inclined to. Competing dehydrated is worse than just being dehydrated.


1. Adam Jetton, et. al., “Dehydration and Acute Weight Gain in Mixed Martial Arts Fighters Before Competition,” Journal of Strength & Conditioning Research, 27(5), 2013

Photo courtesy of Stryder1975 at <a” href=””>en.wikipedia [GFDL or CC-BY-SA-3.0-2.5-2.0-1.0], from Wikimedia Commons.

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