Critical appraisal of a pilot study examining a ketogenic diet as an adjunct therapy in college students with major depressive disorder

Abstract Major depressive disorder (MDD) remains a leading cause of disability worldwide, and innovative adjunctive strategies are needed to enhance treatment outcomes. This critical appraisal examines a recent pilot study by Decker et al., which evaluated a 10–12 week well-formulated ketogenic diet (WFKD) as an adjunct therapy for college students with MDD. In this uncontrolled cohort (n = 16 completers), mean PHQ-9 and HRSD scores decreased by approximately 69–71% (p < 0.001), accompanied by notable improvements in self-reported wellbeing, cognitive performance, body composition, and metabolic biomarkers (e.g., leptin reduction, BDNF increase). These findings suggest that metabolic interventions may exert clinically meaningful antidepressant effects comparable to conventional therapies. However, as a single-arm study with a small, self-selected sample, causality cannot be established, and placebo effects or concurrent counseling may have contributed to outcomes. The authors appropriately call for larger, randomized controlled trials with longer follow-up and diverse populations to confirm efficacy, explore underlying mechanisms (e.g., neuroinflammation, gut–brain axis modulation), and optimize implementation. If validated, integrating dietary strategies into psychiatric and college counseling programs could offer a low-risk, holistic approach to improving mental health outcomes.