UFC Star Alistair Overeem Stopped Eating Meat Over 'Parasites' – Then He Lost So Much Weight Fans Said They'd Never Seen Him So Small: Photos

He spent decades building one of combat sports' most recognizable physiques, but a major change to his diet left the retired heavyweight looking markedly different and prompted concern among some fans. Before-and-after photos can be found at the end of this article.

For much of Alistair Overeem's fighting career, his imposing build was almost as recognizable as his achievements inside the ring and cage.

The Dutch heavyweight competed for decades at the highest levels of combat sports, challenged for UFC gold, and won the 2010 K-1 World Grand Prix, all while maintaining the powerful physique associated with his years as a heavyweight.

By 2023, however, Overeem looked considerably leaner. Images showing his smaller frame spread across the MMA community, where some people struggled to reconcile his appearance with the heavily muscled fighter they remembered.

The change had not simply come from stepping away from competition: Overeem said he had begun detoxing, adopted a different approach to nutrition, and stopped wanting the meat that had once been a routine part of his diet.

Speaking to "Lovin Dubai" in June 2023, the Dutch heavyweight explained that the process began after he started working with a nutritionist whose knowledge immediately impressed him. He shared:

"I started doing detoxing. I have this special nutritionist [...]. When I met him, I instantly knew this guy has knowledge."

The new routine included taking relatively high doses of supplements such as spirulina, coralline, and kelp each morning on an empty stomach. According to the UFC star, it did not take long for him to notice that something else was changing.

"After a couple of weeks, [...] my diet, my appetite changed," he explained. That shift was particularly noticeable because of how accustomed the Dutch heavyweight had been to eating meat.

He revealed that having steak at 8 a.m. had previously been "standard" for him, yet after following his new regimen for several weeks, he found himself no longer wanting it. When Overeem raised the change with his nutritionist, he said he was given an explanation involving parasites.

"'You had parasites in your body,'" the fighter recalled the nutritionist telling him. "This [the supplements] creates an alkaline environment which these parasites do not like. Actually, they will get hurt, and they will die off. And once you get rid of them, your tastes change."

Overeem subsequently attributed his former desire for meat to those purported parasites, saying, "It's not me who needs to eat meat; it's the parasites that influence me. They work through me to make me think I want to eat meat, but it's not me, and once you get rid of them, you don't care." He continued:

"If I eat meat, yes, it's delicious, but then these parasites come in my system. They're gonna move around and do their thing and then all the other things will become less healthy. This [bag of nuts] doesn't create acidity. Meat does, sugar does."

As the Dutch heavyweight spoke publicly about the dietary overhaul, his dramatically leaner appearance attracted attention of its own. Some reactions centered on how quickly his physique seemed to have changed, with one person commenting, "Omg bro that can't be healthy to go through such drastic change in such a short time period."

Another shared, "Looking a little famished there Alistair...If your retired, fine with it. If not get back on the Porterhouses [sic]." The difference was striking enough for another person to joke about Overeem moving far below the heavyweight division, typing, "Dropping to middleweight, damn... Dude is smaller than I've ever seen."

By then, however, maintaining the size required for another heavyweight fight was no longer part of the UFC star's plans. His changing lifestyle coincided with his decision to end a 25-year fighting career.

"This actually ties into what I want to do, because I actually just decided to stop fighting," he said. "This is not my thing anymore." However, for Overeem, there was no suggestion that leaving competition meant leaving physical activity behind.

Instead, he was looking toward what would follow a career that had occupied much of his adult life. "It's been 25 years, right?" he noted. "We're going to do other cool stuff now."

Nearly three years later, Overeem offered a clearer picture of what that new chapter looked like. By March 2026, retirement had changed the purpose of his training rather than his commitment to it, with fitness remaining firmly embedded in his everyday routine.

"Fitness is life," he stated while discussing his post-fighting lifestyle. "Fitness to me determines everything." Injuries that prevented him from exercising had reinforced that view, he explained, because being unable to use his body left him feeling lost and almost depressed.

Those experiences helped shape a retirement routine that still closely resembled the disciplined schedule of a professional athlete. The Dutch heavyweight shared:

"My whole life is scheduled around training. Even after retirement, I train Monday to Friday and take the weekend off. Three weeks on and one week off, this is my schedule. Basically, this is it for the rest of my life."

His approach also extended beyond training itself. Recovery remained important, and Overeem said cold therapy, which had helped him during his fighting career, continued to have a place in his routine.

"I love ice baths; it makes me feel good," he explained. "Cold therapy carried me through fights; it helps me slow everything down in life. Ice baths help me recover, reflect, and reset."

The changes that first drew widespread attention in 2023 therefore came during a much broader transition for the former heavyweight.

After decades spent preparing his body for fights, Overeem had stopped competing, dramatically changed his diet, and continued training on his own terms in retirement. The difference that transition made to his appearance can be seen in the before-and-after photos below.

Before

After