Objective: The authors aimed to test the effect of a therapeutic ketogenic diet (KD) on the psychotic condition, body composition and metabolic dysfunction in schizophrenic patients, as well as to report the compliance with the diet.Method: Two Ecuadorian schizophrenic patients' male and female (twins) aged 22, were included in a six-week controlled-blinded pilot study under the therapeutic KD. Compliance was determined by daily urine measurements (commercially available ketone strips). Body composition was analyzed using bio-impedance (Tanita SC-331S) and the clinical outcomes were assessed by blood, urine and electrocardiogram analysis. The psychiatry condition was evaluated by the PANSS scale and, a two weeks follow-up after intervention was conducted to evaluate patients' health condition.Results: During intervention, after ~15 days of ketosis, PANSS scores decreased in both female (97 to 91) and male (82 to 75) patients. Body fat decreased from 24.5% to 19.8% and 21.7% to 16.8%, respectively. Interestingly, after the third week of the intervention, male patient' liver enzymes were downregulated to normal levels (AST=0-40 U/L & ALT=0-41 U/L). No other significant clinical outcomes were observed during the study. Of relevance, both patients broke the KD in several occasions. Conclusions:The present research showed that a short-time ketogenic diet (KD) has positive effects in the psychiatric condition, metabolic dysfunction and body composition of young schizophrenia patients; suggesting the need of a clinical trial to corroborate its use as a co-treatment.