Comedian and podcast host Joe Rogan tried an all-meat diet for 30 days as part of "World Carnivore Month" in January.
He said that eating nothing but steak, and some eggs and fish, gave him more energy and helped him lose weight.
A major side effect, however, was "explosive uber diarrhea" for the first two weeks. Experts don't recommend the all-meat diet because it's low in fibre, a crucial nutrient for digestion.
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Comedian Joe Rogan doesn't shy away from controversy, using his wildly popular podcast to air conspiracy theories, questionable comments, and other divisive content. Last month, Rogan made himself a contentious talking point by pushing his own diet to the extreme, committing to 30 days of eating only meat, without carbs, veggies, fruits, or anything else.
Rogan decided to embark on the dietary experiment after previously interviewing controversial psychologist Jordan Peterson who, along with his daughter, claimed the carnivore diet could boost health.
But despite high profile advocates like Peterson, and former orthopedic surgeon Shawn Baker, the carnivore diet has been critiqued for severely limiting nutrients, and cutting out a wealth of foods known to be beneficial for human health.
Rogan said the all-meat diet boosted his energy and helped him lose weight
A typical day of eating on the carnivore diet included two meals a day, according to Rogan's Instagram. Breakfast included six eggs or a steak, and for dinner, he would eat another steak, either beef or elk, and occasionally other types of wild game such as bison.
By the end of the diet, Rogan posted that he lost a total of 12 pounds and felt amazing.
"Lots of aches and pains went away, and I have improvements in my vitiligo [a chronic skin condition]," he posted on Instagram.
Anecdotally, many others on the carnivore diet or similar meat-based nutrition plans have shared similar stories of weight loss and mental clarity under hashtags like "meat heals" on Twitter and Instagram.
But there's no scientific evidence to back up those claims. In fact, most nutritionists advise against cutting out whole food groups, particularly vegetables, which are a rich source of nutrients.
"This diet is absolutely ridiculous," specialist dietitian Nichola Ludlam-Raine previously told Insider. "It's massively devoid in nutrients, carbs, and fibre which will most likely leave you feeling lacking in energy."
He suffered severe digestive distress in the form of diarrhea
Even Rogan's otherwise positive review of the carnivore diet wasn't without a caveat. He was blunt and detailed about his issues with digestion during his first few weeks of eating only meat, when he reportedly dealt with severe and frequent bouts of diarrhea.
Rogan treated his Instagram followers to a graphic description of his gastrointestinal distress.
"I haven't sh-t my pants yet, but I've come to accept that if I keep going with this diet it's just a matter of time before we lose a battle," he posted, with a picture of his dinner of liver and bacon.
This side effect reportedly went away after the first two weeks, Rogan said.
Fibre is a crucial dietary nutrient not found in meat and important for digestion and overall health
Rogan's stomach troubles on the all-meat diet were likely linked to an important nutrient found in veggies, grains and other plant-based foods — fibre.
Fibre is a type of carbohydrate the body can't digest, but it's important for regulating digestion, helping moderate blood sugar when you eat, and other important functions.
Proponents of the carnivore diet argue that meat is one of the most nutritious foods on the planet, and can provide all necessary vitamins and nutrients. It's true that animal products like organ meats can be a rich source of vitamins.
But they don't contain the fibre necessary for good digestion and a strong microbiome. A low-fibre diet has consistently been linked to higher risk of disease like cancer, diabetes and heart problems, according to research.
And besides fibre, fresh fruits and veggies also contain micronutrients and other compounds that evidence has found are protective against disease.
"There is no body of evidence that suggests that vegetables cause illness," registered dietitian Heidi Bates said in a recent post from McGill University's Office for Science and Society, as Insider previously reported. "In fact, the opposite is true. There is an excess of evidence linking vegetable consumption to reductions in the risk for heart disease, stroke, diabetes, obesity and certain types of cancer."