Conor McGregor and the dangers of weight cycling

Conor McGregor is risking severe cardiac issues and even death by rapidly moving up and down weight classes according to the Head of Health and Human Performance in DCU. 

By the time McGregor faces Nate Diaz at UFC 196, the Dublin man will have gained 25lbs since his last fight in December. Professor Niall Moyna believes that the Irishman’s extreme weight cycling “can cause arrhythmia, cardiac issues and in many cases, can cause death.”

Crumlin-born McGregor won the featherweight title in December when he fought Jose Aldo at 145lbs. He immediately signalled his intent to move up and fight Rafael dos Anjos for the lightweight title at 155lbs.

The Brazilian broke his foot in training just 10 days before the fight and Nate Diaz was more than happy to step in. However, Diaz informed the UFC that he would be unable to make the designated weight in time for the fight.


A much heavier Conor McGregor at UFC 196 weigh ins. 

The fight will now take place at welterweight (170lbs), a full 25lbs heavier than McGregor’s previous fight. Professor Moyna believes that the methods used to cycle between weights such as extreme dieting and dehydration could have a devastating effect on McGregor’s short and long term health.

“Once you become dehydrated it decreases the amount of blood volume. So the amount of blood pumped out by your heart per beat decreases. Your heart rate increases to compensate for that. Secondly there are huge changes in mood. Big, big mood swings.”

Being moody is far from the worst that McGregor can expect if he persists in cutting and gaining huge amounts of weight.

 “[There would be] a decrease in blood flow to your kidneys and you will also lose a lot of electrolytes, sodium and potassium and that can be fatal. In 1997 that was really the first time that this came to prominence in the U.S when 3 wrestlers died within a 5 week period from weight cycling. They had been trying to lose weight to make competition.”

Professor Moyna is referring to the three American college students who died in 1997 when they underwent strenuous weight-loss workouts to make weight for various wrestling competitions. The youngest, just 19, went into cardiac arrest while on an exercise bike. He had also been refusing liquids.

The second died of heat stroke while exercising in a rubber sweat-suit designed to promote weight loss. The third died of heart malfunction and kidney failure. They were 22 and 21 respectively. It is well known that as well as using diuretics to reduce water retention, McGregor does extra cardio wearing a sweat-suit in the run up to a fight.

Playing the weighting game

The dangers of weight cycling are multiple and Professor Moyna believes that repeatedly going up and down different weight classes is going to have severe health implication both in the short and long term.

“The problem with McGregor is that he is coming up and down in weight and weight cycling, that can negatively affect bone health, and his hormones will be deregulated.”

Fans of the sport will remember Anderson Silva’s leg break the UFC 168. Recognised as the best pound-for-pound fighter on the planet at the time, the Brazilian’s career was dealt a near-fatal blow when he broke both his fibula and tibia while executing a low kick, a regular move in his arsenal. Decreased bone health could certainly increase McGregor’s chances of a similar incident.

But it is safe to say that McGregor remains unfazed. “The only weight I care about is the weight of my cheques,” he said at the recent press conference, “and they’re super heavyweight.”

At an open workout in Las Vegas on Thursday, McGregor was asked if he could possibly move beyond 170lbs to 185lbs.

“Who knows? As I keep growing and keep training and keep eating. My body could change as I get older. I could become that solid block at 170 and then I’d happily go up to 185. It would be like going up to 155 from 145, so I have no problem doing that.”

According to Professor Moyna, a major issue with gaining weight is his ability to regulate the kind of weight he is putting on.

“Severe caloric restrictions coming back down weight is bad but when he tries to put it back on he’ll be trying to regulate between putting on lean tissue and fat tissue, and because he’s putting it on so quickly, he’ll not be able to regulate his lean tissue as well as he could, so he probably would be putting on excess fat.”

In an effort to gain muscle mass rather than fat, McGregor has been known to take protein shakes which often contain creatine, a legal supplement which many professional athletes use. Last November former New Zealand rugby player Jonah Lomu died from a heart attack which was directly linked to severe kidney problems he had from long-term use of creatine as a muscle growth supplement.


Former All-Black Jonah Lomu died last November from a heart attack linked to his kidney disease. He was just 40 years old.

McGregor could be running a similar risk. The practice of gaining a lot of weight with creatine is known to have a deleterious effect on the kidneys. McGregor is also rapidly shedding large amounts of weight, something which Jonah Lomu never did during his professional career.

With the effects of losing and gaining weight proven potentially fatal on their own, it could be said that McGregor is courting disaster by weight cycling in such dramatic fashion.   Despite this, he boasted at a recent press conference, “I don’t care about weight. It makes no difference to me. Wherever it’s at, give me an opponent, and a date, and that’s it.”

But that certainly is not it. During his open workout session on Wednesday, in a rare admission of humanity, McGregor said, “the thing is, making that cut to 145, people only see the build-up, […] people don’t see after the fight, it’s a process to get your body back right after a strenuous cut like that.”

The Dublin man is aware of the difficulties he currently faces making weight at 145lbs. But from the evidence, it seems that his determined efforts to leap up and down in ever increasing bounds will not only be increasingly difficult, but potentially fatal.
by Jack Cahill 

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