A recent systematic review and meta-analysis suggests that ketogenic diets (KDs) may modestly reduce depressive symptoms, particularly when ketosis is biochemically verified and when carbohydrate intake is kept very low. Evidence for anxiety outcomes, however, remains inconclusive, underscoring the need for larger and more rigorous studies.
Background and Methods
The ketogenic diet is a high-fat, moderate-protein, very-low-carbohydrate eating pattern that induces ketosis, shifting energy use from glucose to fats.
The analysis included adults aged 18 and older who consumed fewer than 26% of calories from carbohydrates or less than 50 grams per day.
The literature search covered MEDLINE, Embase, and APA PsycINFO through April 18, 2025, with additional manual searches and clinical registry checks.
Study designs included randomized clinical trials (RCTs), quasi-experimental studies (QSEs), cross-sectional studies, case series, and case reports that used validated psychiatric symptom scales.
Data were extracted by one reviewer and independently verified by two others.
Key Findings
Depressive symptoms: In 10 RCTs, KDs were associated with a significant reduction in depressive symptoms versus control diets (standardized mean difference [SMD] = −0.48; 95% CI, −0.87 to −0.10; I² = 67.2%). The effect was stronger when ketosis was verified, participants were nonobese, the intervention used a very low-carbohydrate approach, or the comparator was a non–high-carbohydrate diet.
Anxiety symptoms: Nine RCTs showed no significant effect (SMD = −0.03; 95% CI, −0.18 to 0.12; I² = 41%). In quasi-experimental studies, anxiety reductions were reported (SMCC = −0.58; 95% CI, −0.81 to −0.36; I² = 0%), but these designs are more susceptible to bias.
Overall patterns: Across nonrandomized designs, depressive symptoms tended to improve consistently (SMCC = −0.66; 95% CI, −0.83 to −0.50; I² = 0%), with concurrent but less consistent reductions in anxiety (SMCC = −0.58; 95% CI, −0.81 to −0.36; I² = 0%).
Limitations and cautions
Small sample sizes and heterogeneous study designs limit generalizability.
Follow-up durations were often short, and adherence/adverse event reporting varied.
Populations were diverse, and outcomes were measured with different scales, which can affect comparability.
Observed associations do not establish causality.
Clinical implications
Ketogenic diets may offer modest improvement in depressive symptoms for some adults, especially when ketosis is biochemically verified and the dietary intervention is tightly controlled.
Evidence for anxiety improvement is not robust; caution is warranted when counseling patients about anxiety outcomes.
Given methodological limitations, clinicians should tailor recommendations to individual context, monitor metabolic effects and mood symptoms, and consider piloting KD strategies within research or supervised settings.
Direct quotes from the study authors emphasize that findings indicate potential therapeutic benefits for depressive symptoms but do not establish causality, and that improvements across populations should be interpreted with caution due to design differences and adherence reporting.
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