Ketogenic Metabolic Therapy (KMT) has moved from case reports to controlled trials in serious mental illness in under five years, and the first randomized trials in treatment-resistant depression and in psychotic disorders were published in 2026. This session reviews what the outcome data now show for ketogenic and related metabolic interventions in schizophrenia, bipolar disorder, and major depression, where the evidence remains thin, and how the findings translate to practice. The talk opens with the clinical gap that motivates metabolic psychiatry: excess cardiometabolic mortality, 30 to 50 percent treatment resistance across diagnoses, and persistent functional impairment despite symptom reduction. It then summarizes the mechanistic rationale for KMT in brief, drawing on the century-long precedent in drug-resistant epilepsy and on ketone bodies as an insulin-independent brain fuel and signaling molecule. The core of the session is an evidence update. Single-arm and retrospective studies (Danan 2022, Sethi 2024, Campbell 2025) reported clinical remission in a substantial minority of refractory inpatients, resolution of metabolic syndrome in adherent outpatients with schizophrenia or bipolar disorder, and reduced brain glutamate on MR spectroscopy in euthymic bipolar disorder. Two randomized trials now extend that signal. In treatment-resistant depression, a six-week ketogenic diet outperformed an active control diet at the end of the intervention, and the benefit tracked adherence, which fell once dietary support ended (Gao 2026). In schizophrenia-spectrum and bipolar I disorder, a one-month randomized comparison against diet as usual produced significant improvements in weight, HbA1c, and insulin resistance, and a four-month extension produced improvements in depressive, positive, and negative symptoms and in cognition, with ketone levels rather than weight loss predicting symptom change (Abram 2026). A 2026 systematic review and meta-analysis of 73 studies places these trials in context and quantifies the cognitive benefit in neurocognitive disorders. Evidence that reversing insulin resistance with metformin improves treatment-resistant bipolar depression (Calkin 2022) is presented as a convergent test of the metabolic hypothesis. A shorter section reviews outcomes for interventions that share KMT’s biological targets and compound its effects: structured exercise, bright light and circadian alignment, mind-body practice, and selected nutraceuticals including creatine. The session closes with practice guidance on patient selection, metabolic monitoring, and shared-decision deprescribing, drawing on the 2026 modified Delphi consensus on KMT in serious mental illness and on the long-term antipsychotic dose-reduction trials.