Dr. Terry Dubrow, Jillian Michaels and More Celebs Sound Off on the Keto Diet

The Botched surgeon thinks that the popular weight-loss fad is "kind of a dumb diet," saying, "Yes, you can eat super high-fat foods and protein and essentially no carbs, and use ketones as your fuel, but you can’t do it for the rest of your life. It’s obviously not the way humans are supposed to eat. You must have fruits and vegetables and fructose and carbs. You’re never going to convince any kind of doctor that you’re not supposed to have fruits and vegetables, with their cancer-preventing nutrients and antioxidants."

His dislike for the diet lead him to co-create a new diet with his wife, Heather: The Dubrow Keto Fusion Diet.

According to Dubrow's plan, dieters fast for 12 hours, then they follow a keto diet for eight hours, and then they follow that up with four hours of eating fruits, vegetables and carbs they miss out on during the keto hours.

The Real Housewives of Orange County star has said keto "concerns" her, adding that she tried it but had to quit keto after only a month because she experienced what's been called the "keto flu"—influenza-like symptoms such as body aches, fatigue, dizziness and nausea.

According to Women’s Health, doctors believe that its because the body is going through withdrawal as it switches to burning fat for energy instead of carbs, a process called ketosis (which is how the keto diet earned its name).

One year after quitting the Keto diet, Judge star doubled down on her claims that the diet is "not healthy." She told one of her fans on Instagram, "Couldn’t wrap my brain around eating so much fat. Just not healthy in the long run.”

The former Today Show host gushed about the diet when she tried it in summer 2018. She said on her Instagram stories, "So I've been doing the keto diet for a week now and I actually do feel better. The fourth or fifth day, I felt a little shaky and headachy, but I feel much better." It sounds like she experienced the keto flu, which can happen to some people giving the diet a try.

Couric did advise her fans to talk to a doctor if they were interested in the diet.

“Last summer, I kind of dove into the keto [diet] world and enjoyed it,” the Food Network star recently told PEOPLE. “It was a good exercise.”

Though she says she has since “settled back into a more sustainable, realistic way of eating,” her experience with cutting back on grains and sugar influenced her sixth cookbook, New Frontier, which will hit shelves October 22 and will be full of “suggestions for how to lighten up an otherwise really carb-heavy dish.”

Her husband Mark Consuelos might be all about the diet (see slide seven), but for the Live with Kelly and Ryan co-host keto is "something I could never do," she told Bon Appetit. "I just don’t have that level of discipline. Mark says that I’m carb-o, because I always eat his bun if he gets a burger. And the fries. But you know, I work out, so I feel like I’m allowed. I’m 48, I’m entitled, and I’m eating whatever I want to eat."

The celebrity trainer is so against the diet that she recently called it a "bad plan."

"I don’t understand. Like, why would anyone think this is a good idea?” Michaels, 44, said in a video for Women’s Health.

Instead, she recommends eating a well-rounded diet. “You don’t eat processed sugar, you don’t eat processed grains, and to make a very long story short: avoid the keto diet,” she said. “Common sense. Balanced diet is key.”

The Celebrity Big Brother UK star, 44, shared a side-by-side photo of herself on Instagram in which she gave fans a comparison of how she looked before and after giving birth to 17-month-old daughter Batel Lu.

Since adopting the keto diet in March, Jameson says she has lost more than 80 lbs.

"It’s not only given me physical results, I feel happier, smarter, and much more confident," she says.

After gaining 25 lbs. while recorvering from four surgeries to help her vision in her left eye, the reality star turned to keto.

"It’s not that bad. It’s like, cheese, eggs, protein, meat. And you honestly lose weight with that,” she said in an interview with BUILD Series. “That’s what I’ve been going back to, and I’ve started losing a couple pounds. But it actually, really works.”

The Today cohost tried the high-fat, low-carb diet for seven weeks, but said she didn't lose a pound.

“It’s not even doing anything,” Guthrie, 46, said on Watch What Happens Live with Andy Cohen. “I haven’t lost anything! I haven’t lost a thing. But you know, I’ve eaten a lot of bacon and I’ve liked it.”

"Mark is doing that keto diet," his wife, Kelly Ripa, said on Live with Kelly and Ryan on Tuesday. "Since he's been doing that I've been on a mostly carb diet. He'll have the burger but he won't have the bun. Then I see that little bun sitting there with burger juice on it and the condiments and yeah, I'm not a big meat eater so I just eat that bun with the lettuce and the tomato and I'm a happy camper."

The reality star, 40, was first introduced to the plan in 2017 after her doctor found high levels of mercury and lead in her system. She later praised it, calling it a "really positive experience for me.”

“I would make broccoli rice or cauliflower rice to at least feel like I was eating some carbs,” she wrote on her blog. “Then I would add protein, so I often ate grilled chicken and fish over broccoli rice, cauliflower rice or spaghetti squash. I mixed in roasted vegetables, fresh salads with homemade dressing, and smoothies made with avocados and bananas.”

The Today show meteorologist says he's lost 10 lbs. in two weeks since starting the keto diet.

"The toughest part is not eating bread," he tells PEOPLE. "Last weekend I was in Paris to drop my daughter off at school for her sophomore year. I think it's the first time in 35 years going to Paris, but I did not have any croissant or any bread."

The actress told PEOPLE in April about how she manages her keto diet by cooking a lot of meals at home that follow the trendy, low-carb, moderate protein and high-fat eating plan.

“I don’t really eat pasta, anything with sugar, it’s very much meat-based,” she said. “I eat meat, I enjoy chicken and beef and a lot of vegetables.”

She adds that she includes healthy fats in her diet "all day long."

“Avocado, oil, coconut oil and I use butter, but don’t have any sugar. So when your body gets trained to burn fats, it’s constantly on fat-burning mode—that’s the secret,” she said.

To prepare for her starring role in Tomb Raider, the actress's trainer Magnus Lygdback put her on the keto diet to maintain muscle mass and shed fat.

She ate a lot of fish and seafood for protein plus MCT oil, avocado, and coconut oil as a fat source, Lygdback told Popsugar. Vikander also filled up on vegetables but never went over 25 grams of carbs a day.

The Jersey Shore star created an Instagram account dedicated to documenting his keto diet.

"I’ve discovered the fountain of youth. You ready for it?" he writes. "Stop eating sugars and grains and instead 98% of the time eat real food like whole eggs, bacon, butter, fatty steaks, fatty fish and plants and exercise a few times a week. When I ate sugars and grains I was 50lbs heavier and looked 10 years older."

While guest starring on the Rachael Ray Show, the actress opened up about how she stays motivated through intense workouts: "No carbs. No dairy. No refined sugar. [It’s] eating real foods. It’s honestly high-fat, high-protein. I think that we’ve been brainwashed to think that fat is bad, but really, it’s what going to make you feel fuller longer. And your body can burn it and use it as fuel."

The former NFL star loves adding avocados to his daily diet as part of the keto program. "I have to take in a lot of fat, and the number one fat comes from avocados," he told GQ. "It's a super food. And even if that's not your diet, it's incredible food for you. I put them in my smoothies, guacamole, a bunch of different things. For me it's more than just trying to stay in shape for sports, it's a way of life, of trying to be healthy."

The eldest Kardashian is looking to try keto again after being introduced to it in 2017 by her doctor. She posted her opinion about the controversial diet on her app, saying "it was a really positive experience for me.”