Keto for Depression: What the First Randomized Trial Actually Shows

When standard antidepressants stop working — a situation doctors call “treatment-resistant depression” — patients are often left without good options. But a new randomized clinical trial published in JAMA Psychiatry suggests that what you eat might matter as much as what you swallow from a pill bottle.

The study: 88 people with treatment-resistant depression were randomly assigned to either a ketogenic diet or a control diet emphasizing fruits, vegetables, and unsaturated fats. Both groups received equal dietitian support. After 6 weeks, both groups improved — but the keto group improved more.

The Numbers

Keto group: PHQ-9 depression scores dropped by 10.5 points on average
Control group: Dropped by 8.3 points
Difference: The keto diet showed a statistically significant advantage (Cohen’s d = -0.68)

That effect size — 0.68 — is considered “medium” in research terms. For context, many antidepressants show effect sizes around 0.3-0.5 compared to placebo. So while this wasn’t a miracle cure, it’s a meaningful signal.

What Makes This Study Different

This wasn’t another observational study or case report. It was a proper randomized controlled trial with:

Active control: The comparison group wasn’t “do nothing” — they followed a healthy diet with dietitian support
Prepared meals: Keto participants received actual food (<30g carbs/day), removing compliance guesswork
Treatment-resistant patients: These weren’t people with mild, easily-treatable depression
Published in JAMA Psychiatry: One of the most rigorous peer-reviewed psychiatry journals

The researchers also tracked participants for 12 weeks total. By week 12, the between-group difference narrowed and was no longer statistically significant — though the keto group maintained their improvements.

Why Would Diet Affect Depression?

The brain runs on energy. In depression, something often goes wrong with how neurons produce and use that energy — a concept researchers call “bioenergetic dysfunction.”

Here’s the theory: ketones (the fuel your body makes on a keto diet) may provide an alternative, more efficient energy source for struggling brain cells. Some research suggests ketones also:

Increase GABA (a calming neurotransmitter)
Reduce inflammation in the brain
Improve mitochondrial function (your cells’ power plants)

This doesn’t mean keto is a replacement for psychiatric care. But it suggests metabolic interventions deserve a seat at the table.

The Caveats

Honest reporting requires noting what this study doesn’t prove:

Short duration: 6 weeks isn’t long. We don’t know if benefits persist — or if the control group catches up over time.
Small sample: 88 people is enough for preliminary evidence, not definitive proof.
Secondary outcomes didn’t differ: Anxiety, anhedonia (inability to feel pleasure), and quality of life weren’t significantly different between groups.
Modest effect: The 2.2-point difference in PHQ-9 scores is statistically significant but clinically debatable. Some would call it meaningful; others would want to see more.
Adherence matters: Participants received prepared meals and weekly dietitian support. Real-world results might differ when people manage their own food.

Practical Takeaways

If you’re dealing with depression — especially treatment-resistant depression — this study suggests:

Talk to your doctor first. This isn’t medical advice, and changing your diet while on psychiatric medications requires professional guidance.

Metabolic health matters for mental health. Whether or not you go full keto, stabilizing blood sugar, reducing processed foods, and eating nutrient-dense whole foods may support brain function.

Electrolytes are non-negotiable on keto. The study provided dietary support, which likely included electrolyte guidance. Sodium, potassium, and magnesium depletion can cause fatigue, brain fog, and mood issues — exactly what you’re trying to avoid.

Give it time. The keto group showed meaningful improvement by week 6. If you try a metabolic approach, commit to at least 4-6 weeks before evaluating results.

Support structures help. Both groups had weekly dietitian check-ins. Having accountability — whether from a professional, app, or community — improves outcomes.

The Bigger Picture

This study adds to a growing body of evidence connecting metabolic health and mental health. It doesn’t prove keto cures depression. But it does suggest that for some people — especially those who haven’t responded well to standard treatments — dietary interventions might be worth exploring alongside conventional care.

The fact that JAMA Psychiatry published this signals that mainstream medicine is taking metabolic psychiatry seriously. Expect more research in this space.

For now, if you’re curious about keto for mental health, approach it as one tool in a larger toolkit — not a magic bullet, but a legitimate option worth discussing with your healthcare team.

Source: Gao M, Kirk M, Knight H, et al. A Ketogenic Diet for Treatment-Resistant Depression: A Randomized Clinical Trial. JAMA Psychiatry. 2026. doi:10.1001/jamapsychiatry.2026.0077