Ketogenic diets earned some renewed (if dubious) attention last week when Health Sec. Robert F. Kennedy Jr. touted the mental health benefits of the high-fat, low-carb meal plan.
“We now know that the things that you eat are driving mental illness in this country,” Kennedy told Tennessee state lawmakers in Memphis.
He then delivered his punchline, insisting that a Harvard doctor had “cured schizophrenia using keto diets.”
According to The New York Times, Kennedy seemed to be citing a 2019 Psychology Today piece by Christopher Palmer, M.D.
While Kennedy’s oversimplification of preliminary data leaves a lot to be desired, new research suggests the diet might offer small, short-term antidepressant benefits for people with treatment-resistant depression. That being, the evidence only points to modest benefits that might be a challenge to sustain, according to the randomized clinical trial in JAMA Psychiatry.
The study appears to be one of the first controlled trials to rigorously test ketogenic diets as an adjunctive treatment for depression that has failed to respond to standard medications.
Methodology – and Measurable Results
Researchers enrolled 88 adults across the United Kingdom with moderate to severe treatment-resistant depression. The participants then randomly assigned each of them to follow either a ketogenic diet or a control diet for six weeks. Both groups received equal nutritional support.
At first, depressive symptoms fell off sharply in both groups. But by the six-week mark, those assigned to the ketogenic diet showed a slightly greater improvement on the Patient Health Questionnaire-9 (PHQ-9). On average, PHQ-9 scores dropped by more than 10 points in the ketogenic group compared with 8.3 points in the control group.
“The effect was real, but modest,” the authors emphasized.
By 12 weeks – six weeks after the end of dietary support – the difference between groups contracted even more – so much so that it was no longer statistically significant.
Additionally, improvements in other areas also appeared to be mostly similar between diets. The only exception? A small, transient advantage for anxiety at week 12 in the ketogenic group.
A Matter of Design
The researchers point out that the control diet wasn’t completely without treatment. The team asked participants to add a daily serving of fruits or vegetables and swap saturated fats for unsaturated plant oils. The authors meant for those changes to be credible, but unlikely to meaningfully influence their depressive symptoms on their own.
The researchers also matched both groups for contact time with trained dietitians or health coaches. It was a move meant to curb placebo effects and nonspecific therapeutic benefits.
And that design tweak made a difference. Depression severity fell quickly in both groups. And that reinforced just how effective a structured support system (along with managed expectations) can be in treatment-resistant depression.
Adherence Remains a Challenge
The study’s authors added that participants struggled to stick with a ketogenic diet – even with a robust support system in place. Researchers provided participants with prepared meals and snacks, along with ketone-testing strips. Most of the participants achieved measurable ketosis during the six-week intervention.
Once that support ended, however, fewer than one in 10 participants stuck with the ketogenic diet. Almost half of them stopped following it altogether.
But perhaps most importantly, the degree of ketosis didn’t seem to predict symptom improvement. Participants with higher ketone levels didn’t show greater reductions in depression scores. That finding casts doubt on whether ketones were responsible.
Subgroup analyses hinted that people with more severe depression at baseline might have benefited more than those with more moderate symptoms. Among participants with higher PHQ-9 scores, the ketogenic diet produced a larger short-term advantage than the control diet.
The authors warn, however, that these were exploratory results based on a small sample size.
‘Cautious Encouragement’
Taken together, the results offer cautious encouragement. But it doesn’t come without limits.
“This randomized clinical trial provides preliminary evidence that a ketogenic diet may confer small antidepressant benefits when added to standard care,” the authors concluded. “However, the clinical relevance remains uncertain.”
For now, they argue, we can’t accept ketogenic diets as broadly scalable depression treatments. Maintaining such restrictive eating patterns isn’t easy. And the modest benefits might not justify the burden.
Further Reading
Ketogenic Diet Shows Promise for Bipolar Disorder
Could Mindfulness Crack Treatment-Resistant Depression?
Can Physical Changes – Like a Keto Diet – Help Mental Illness?
