RFK Jr. claims he lost 20 pounds in 20 days, gained mental clarity on extreme diet

Health and Human Services Secretary Robert F. Kennedy Jr. revealed the details of his extreme, highly restrictive diet centered on meat and fermented foods.

"I'm on a carnivore diet," Kennedy said during a recent interview on USA TODAY's "The Excerpt" podcast.

Kennedy said he follows the diet the "whole day," every day.

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"That may not be right for other people, but I lost 40% of my visceral fat within a month," he said on the podcast, referring to the fat that surrounds internal organs and is linked to higher risks of cardiovascular disease.

He also claimed improved mental clarity and said he lost 20 pounds in 20 days after switching to the diet. He acknowledged some of the benefits could be due to the placebo effect.

The carnivore diet is a meal plan that includes consuming only animal products such as meat, dairy and eggs, Fox News Digital has previously reported. 

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The health secretary, who turned 72 this month and celebrated with a hefty steak, pairs the diet with foods that are fermented, typically meaning they are soaked, salted or cultured to let natural bacteria or yeast break down sugars over time. 

Cabbage, for example, becomes sauerkraut when it's salted and left to ferment; milk turns into yogurt or kefir when live cultures are added; and soybeans become miso through a long fermentation process.

Experts say fermented foods can support gut health, boost immune function and reduce inflammation by increasing beneficial bacteria in the gut. Some also note the fermentation process may produce compounds linked to better mood, energy and sleep.

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Kennedy is known to eat steak with fermented vegetables for breakfast and even bring his own sauerkraut to restaurants - a habit his wife, actress Cheryl Hines, joked about with The Cut. 

"I'll have my little clutch, one of my good bags that I only take out every once in a while because I want to keep them nice, and he'll hand me a bag of sauerkraut and say, 'Can you put this in your bag?'" Hines told the outlet.

"People will say, 'Ew, what's that smell?'" she added, saying she responds, "'Don't worry about it, it's my husband's dinner.'"

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Kennedy's comments come amid the Trump administration's updated federal dietary guidelines, which place more emphasis on protein and whole foods while easing decades-old restrictions on saturated fat.

Kennedy's personal eating habits are more extreme than the updated guidelines he helped unveil and experts have warned that the carnivore diet, in particular, is highly restrictive and needs more research.

"We don't have gold-standard, evidence-based medical research to support the carnivore diet's long-term health claims," Dr. Mia Kazanjian, a board-certified radiologist in Connecticut, told Fox News Digital.

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"Eliminating fruits, vegetables and whole grains is dangerous because it deprives people of essential vitamins, minerals, fiber, phytochemicals and antioxidants," Kazanjian added.

Fermented foods like sauerkraut and kimchi have less fiber than plants, so they are not a replacement for plant nutrients, she noted, and a diet centered on animal foods can also increase LDL cholesterol, raising the risk of heart disease and stroke.

Other potential risks associated with the carnivore diet include kidney stones, gout and bone loss, according to experts.

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Kazanjian recommends speaking to a doctor before starting any new diet. "As a physician focused on cancer prevention, I recommend a Mediterranean diet, largely plant-based, with whole grains, fruits, vegetables and lean proteins, for optimal health and longevity," she added.

Later in the interview, in response to a question about peptides and supplements, Kennedy reiterated, "I don't want to make myself a role model for what people should do and shouldn't do."

He also said "gold standard science," not his personal opinions, influences the administration's public policy.

Fox News Digital has reached out to the HHS Department for comment.

Additional reporting by Fox News Digital's Melissa Rudy and Andrea Margolis.