We’ve been told our whole lives that fruits, vegetables, and whole grains are the keys to a healthy diet. But what if that’s all wrong, and the true key to health lies in animal-based products and nothing else? 

That’s the idea behind the carnivore diet, an extreme eating regimen that limits people to only meat, eggs, and certain dairy products. 

Again, it sounds crazy considering that countless scientific studies have found that diets high in red meats lead to cancer and other diseases. Despite that, countless people have preached the benefits of a carnivore diet—saying it’s helped them lose weight, heal their digestive tracts, increased their testosterone, and more. 

The latest celebrity to endorse the diet is popular podcast host and UFC commentator Joe Rogan. In an Instagram post, he revealed that sticking to it for the month of January helped him shed 12 pounds and lose his belly and love handles. He added, “Lots of aches and pains went away, and I have improvements in my vitiligo. I’m impressed.” Vitiligo is a skin condition Rogan suffers from, which causes skin discoloration.

Take a look at Rogan’s results. 

Rogan’s unsure if he’ll continue the carnivore diet, but called the month “very beneficial.” It should also be noted he admits the diet made him take several trips to the bathroom, which is apparently normal on the diet. 

“The explosive uber diarrhea stopped around 2 weeks in. It’s been totally normal last two weeks,” he wrote.

Rogan’s far from the only celebrity to try the carnivore diet. Here are four other big-time names who ate like cavemen.