‘Biggest Loser’ Trainer Says Popular Keto Plan Is a ‘Terrible, Terrible Idea’

By Zachary Stieber

A trainer on the television show “Biggest Loser” slammed the popular keto diet, calling it a “terrible, terrible idea.”

“Your cells are literally made up of those three macronutrients,” Jillian Michaels said during an episode of the “Adulting” podcast, according to People magazine. She emphasized the importance of eating protein, fat, and carbohydrates.

“The best diet for anti-aging” would be one that encourages people to eat a “balanced, clean version of protein, fat, and carbs,” Michaels said.

“That’s just one of the many reasons why keto is a terrible, terrible idea. People can criticize me all they want, but the bottom line is, it’s science and the science is there—and [keto] is bad for your overall health and wellness.”

Jillian Michaels attends PETA's 35th Anniversary Party.
Jillian Michaels arrives at PETA’s 35th Anniversary Party in Los Angeles, Calif., on Sept. 30, 2015. (Frazer Harrison/Getty Images)

Michaels said she wasn’t disputing claims that people who follow the diet have reversed insulin-related health issues like diabetes but said that other diets that she believes are healthier can do the same thing.

“We can accomplish those things … without going into ketosis,” she said, referring to a metabolic process that has the body burning stored fat for daily energy as opposed to glucose.

She also said that keto can have negative effects on the liver and thyroid. “I promise you it’s not good for you and there are better ways of doing it,” she said.

Michaels’ latest opposition came several months after she spoke out against keto in a video for Women’s Health.


“I don’t understand why anyone would think this was a good idea,” the celebrity trainer said in the video. She called the diet a “bad plan” that requires “starving your cells” in order to lose weight.

“Your cells, your macromolecules, are literally made up of protein, fat, carbohydrates, nucleic acids,” she added. “When you do not eat one of the three macronutrients—those three things I just mentioned—you’re starving your cells. Those macronutrients serve a very important purpose for your overall health and wellbeing. Each and every one of them.”

In a blog post in April 2018, Michaels said the diet did have some positive aspects.

“First, what exactly is a ketogenic diet? Well, it’s when the body doesn’t have enough glucose or glycogen to run on so it starts breaking down fats for energy. Ketones are the byproduct of that process. Sounds awesome right? Well, to a certain extent this overall concept is a good one until it’s taken to the extreme. In order to understand what this looks like, let’s first go over the potential upsides of this type of diet,” she wrote.

“Compared to our modern day western diet that is laden with cheap processed grains and sugars, this diet is a godsend. Because it inherently eliminates all that crap it dramatically lowers insulin levels and improves insulin sensitivity.”

people eating pizza in Italy
People eating pizza in Bologna, Italy, on Aug. 29, 2018. (Roberto Serra/Iguana Press/Getty Images)

She also said that “ketones have a neuro-protective component where they can inhibit something called amyloids, which are a type of plaque that can build up—in this case in the brain.”

The downsides of the plan, though, she claimed, don’t make it worth doing.

Not all trainers are against the diet. Kirsty Godso told Well and Good in 2017 that she had gone fully over to the plan seven years prior.

“For the first four days, I felt so tired and grumpy. Cutting out fruit was really hard for me and I also had a pretty bad obsession with gummy candy. Giving that up was hard. But I stuck with it and a week into my newfound eating plan, I felt a huge shift in my body—I felt amazing. “Wow, I am never going back,” I thought. And I haven’t. I’m less strict now—I eat fruit sometimes—but most of the foods I cut out, like rice, I just never added back in because I realized that I not only didn’t need them, but I felt so much better without ’em,” she said.

“What I love about keto is how livable it is. I never have to think too hard about meal prep or what I’m going to eat when I go out with my friends. You don’t have to put your life on hold to do it. I also think it shows people how to have a healthier relationship with fat, which is actually really good for you. Eating this way really nourishes your body, which is why I’m so wild about it. I’ll be eating this way forever.”