Widely criticized keto diet study retracted

A 2025 paper claiming the keto diet does not promote the formation of arterial plaques has been retracted after widespread criticism of the study’s methods and claims. The journal found “the identified errors are too great to be corrected with a corrigendum,” according to the March 11 retraction notice.

In April 2025, JACC: Advances published the study, which looked at plaque build-up in 100 otherwise generally healthy people who had experienced an increase in their cholesterol levels while being on a keto diet. The study claimed scans performed one year apart by the company Cleerly showed the diet was not associated with the development of arterial plaques. 

This finding went against what previous studies had found, and it led to what Wired called “a new war in the nutrition world.” 

Critics began flagging the paper soon after publication, including in a May 2025 letter to the journal that raised other concerns, including “selective reporting” of data, questionable statistical analysis and too short a timeframe for the study. Others noted that one of the paper’s authors, Dave Feldman, is “a software engineer and entrepreneur without a medical license or training, who has devoted himself to all things keto and cholesterol.”

Three of the paper’s authors — Nicholas Norwitz, Adrian Soto-Mota and Feldman — told Retraction Watch they didn’t have access to the data before the study was published and did not know the analysis by Cleerly was not double-blinded. They first saw the data after publication and alerted the journal “immediately,” they said. They advocated for the publishing of an expression of concern, which was attached to the paper in January. They also said they were unaware coauthor James Earls was chief medical officer at Cleerly when the data were collected. 

In a Substack post about the retraction, Norwitz wrote they purposefully did not have access to the data until after publication. “Everyone who isn’t involved in the statistical analysis toward the original findings is appropriately ‘blinded’ from the raw data in order to protect the integrity of the process,” he wrote. “However, after publication, the raw, anonymized data was then provided to the Citizen Science Foundation,” which funded the study, “and thus [to] Dave Feldman, who did a deeper analysis and found a number of anomalies.” Feldman is the founder and president of the foundation.

Norwitz told us he wished he had reviewed the data before publication. “The responsible thing at the time seemed to be forfeiting access until publication. That way, nobody could reasonably accuse me of putting my finger on the scale or influencing the analysis,” he said. 

“My real hindsight correction is that CSF should have required explicit, documented quality-control assurances for any outside vendor supplying analytical data to the study, including provisions for blinded re-analysis if serious concerns arose,” Feldman told us. “I did not anticipate that we could receive a dataset from a major commercial provider, later identify highly anomalous patterns, and still be unable to obtain a direct quality-control resolution of those concerns. That is the part I would never leave to assumption again.”

A representative from JACC: Advances told us Earls disclosed his affiliation with the company when the manuscript was submitted, and upon acceptance of the paper, he told the journal he held equity in Cleerly. The publication noted Earls’ Cleerly affiliation but did not disclose the equity stake.

In January, six members of the research team posted a preprint reporting a reanalysis of the data using an “independent, blinded confirmatory analysis” by the company HeartFlow. They told us the preprint is undergoing peer review at a different journal and said they addressed critics’ concerns in their new manuscript. 

Earls is no longer listed as a coauthor with the group and no longer listed as CMO at the Cleerly leadership webpage. Christy Sievert, public relations manager for Cleerly, declined to answer questions, including about Earls’ apparent change in position and why the company did not double-blind the data analysis. 

Brad Stanfield, a family medicine doctor in New Zealand, and an outspoken critic of the study, told us the reanalysis “raises new concerns rather than resolving the old ones.” 

“The retraction was warranted, and the re-framing of the same data as confirming the original story is, in my view, more advocacy than science,” he said. 

Internist Michael Mindrum, another critic of the now-retracted study, said he sees improvement in the new analysis and acknowledged the authors responded to some of the criticisms of the original paper. In his view, however, “this whole endeavor is at the intersection of social media grifting and medical science. It is all unfortunate.” He said it was clear the authors “will try to fit whatever data is there into their ‘narrative.’” 

Mindrum called two of the authors, Norwitz and Feldman, “social media influencers with an outsized media footprint.”

In his post on Substack, Norwitz wrote he was “over-the-moon happy” to be retracting the original paper because the findings remain “incredibly robust” and should now be published without engendering the controversies that affected the original article.

He also took aim at what he called the “embarassing” and “seemingly willful ignorance of some of our medical and academic detractors.”

But Stanfield disagreed that the central claim held. “If the original methodology was sound enough to promote as revolutionary, it shouldn’t need retraction. If it needed retraction, the promotional campaign that accompanied its release was, at best, premature,” he said. At the time, the Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, where three of the authors are employed and where the scans were performed, announced the work as heralding a paradigm shift. 

“The public, including patients making clinical decisions about their own LDL, deserved more humility from the start,” he said.

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