I ask this question b/c my recollection of early matches in the modern sport is that there were no weight classes, which I believe to be a reflection of the old days of no-holds barred competitions. But it's undeniable that the sport has blossomed in recent decades, becoming arguably the predominant combat sport worldwide. It occurs to me that the rule changes during this period may be a factor that has allowed it to flourish.

  • How has the introduction of weight classes influenced the modern sport of Mixed Martial Arts?
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    Other combat sports have tried to avoid weight classes for a time. Kyokushin karate, judo, and BJJ all have robust open-weight competitions. The results are instructive: usually the heavier competitor wins, but smaller fighters have been lucky or skilled enough to overcome disparities. Commented Nov 8, 2020 at 15:37

2 Answers 2


While in MMA training, people have to rotate partners, and the weight, sizes, and genders are all going to be different. During training is where you learn to deal with bigger opponents. It's actually encouraged in order to motivate you to become more skilled.

It's well known that weight and reach makes a big difference in outcomes of fights of all kinds, including MMA. The UFC and other MMA venues originally had no weight classes, and it wasn't so much because it was trying to be "pure". It was mostly because there weren't enough competitors to have weight classes. As the number of competitors increased, weight classes emerged. And the weight classes themselves can change over time because of increased competition.

But that really doesn't change how MMA is trained. You'll still need to train with partners of all different body types.

A question one might have is: Would MMA's techniques or strategies no longer work if the opponent was much larger?

The answer is NO. MMA techniques and strategies aren't optimized just to fight people of the same weight class. They have to work no matter what.

Instead, if you want to win against a much larger opponent, you're going to have to be much more skilled than your opponent is. That general rule holds for fighting in general, not just MMA.

MMA doesn't have rank, so I'll use BJJ as an example. A 100 pound woman who's a black belt in BJJ will have difficulty fighting a 250 pound muscle-bound man who's a white belt in BJJ. She may even lose. She needs to be much more skilled than he is in order to win. Her techniques won't change. Her strategies won't change. But she needs to have trained so much that her movements are smooth, fast, and correct. She gets that over time by continuously pressure testing her skills against larger opponents. And that's something that's encouraged in BJJ training.

There are other topics to consider when discussing weight classes. By reducing the amount of weight between weight classes, it can make it easier for fighters of one weight class go down or up a weight class. And almost invariably, fighters will weigh one or two weight classes higher during training. They have to lose a lot of water weight and fat to cut weight for the weigh-in. Some cut too much and end up hurting their performance on the day of the fight. Those that don't do this cutting and just fight at their natural weight will end up fighting someone who's naturally much heavier. These issues can greatly effect outcomes of fights.

Hope that helps.

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    Fighters don't change strategies based on their opponents size?
    – mattm
    Commented Nov 6, 2020 at 22:53
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    They certainly must change their own strategy to fit their and their opponent's strengths and weaknesses. But I said that MMA isn't optimized to fight at your own weight class. As if to say, hey, our stuff won't work unless your opponent is +/- 10 pounds from you. As if to say your basic arm bar no longer works just because the guy is 2 weight classes up. It still works. You'll need to be quicker, smoother, and stronger when applying it on that guy than you would necessarily have to when applying it on someone of the same weight class as you but the same skill level as that guy. Commented Nov 6, 2020 at 23:06
  • Perhaps I'm reading more into the original question from Duke. But there is a tendency for traditionalists who ask this question to conclude or imply that MMA is not as good as their traditional martial arts for the street, because MMA is optimized for sport rules. They would argue that the rules of MMA (including weight classes) means that it's dangerous to use for real fights and self-defense. I disagree. But that's a much larger discussion. Commented Nov 6, 2020 at 23:11
  • @SteveWeigand The true intent of my question was to suggest that the introduction of weight classes facilitated the contemporary sport, which is undeniably the dominant combat sport in this era, as have other rule changes since the introduction of the modern sport, spearheaded by the Gracies, surely have. (I quite like the idea that Harrison could dominate any living grappler, regardless of weight class:)
    – DukeZhou
    Commented Nov 6, 2020 at 23:30
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    @DukeZhou We know that size matters from countless numbers of fights. We know that in order for a smaller person to defeat a larger person reliably, it requires that the smaller person have more skill. Those are facts. It's exciting when a smaller opponent defeats a bigger one. Spectators love it. But it's very rare these days. MMA today is so competitive. In the early days before MMA was even a thing, the skill levels were radically different. You had people who were absolutely delusional about their ability to fight. It's no wonder smaller more skilled people defeated bigger opponents. Commented Nov 6, 2020 at 23:39

I think it's not an unreasonable assumption that the introduction of weight classes, and movement away from old-school no-holds barred and Gracie Rules has greatly facilitated the contemporary sport of Mixed Martial Arts.

(This should in no way be taken as disrespect toward Brazilian Jujitsu and the Gracie family, as they were the original drivers of the modern sport. But there was also an element of hype and self-promotion in promoting the idea of an "ultimate martial art", which again, should not be taken as a slight in that the greatest fighters, from Muhammad Ali to Connor McGregor, understood that promotion is an important part of the sport, and used it as effectively as their in-ring skills.)

  • It's facilitated the sport by creating a "level playing field" where weight differential is no longer a factor, bringing the focus back the relative skill of equally matched competitors.

This brought MMA more into line with the most prestigious combat sports, such as Boxing and Olympic Judo.

  • It's likely made the sport of Mixed Martial Arts safer, which also facilitates the sport.

There was a period when it was difficult to find places in the USA to hold competitions b/c the sport was considered too dangerous, and the response to that were rule changes that in no way diminished the sport, but allowed it to flourish and extend it's popularity.

Also ask yourself, while it's probably true that McGregor could take most fighters of any weight class, is it in McGregor's interest to fight heavyweights? Is it best for the sport to have McGregor, already considered one of the all-time greats, fighting heavyweights or having the longest possible career?

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