BACKGROUND: The low-carbohydrate, high-fat ketogenic diet has been popularized in the press recently, touting multiple health benefits such as weight loss and increased energy. In this diet, participants intentionally push themselves into a state of ketosis and usually do not develop metabolic complications or illness unless put under certain circumstances such as stress and prolonged fasting.

CASE REPORT: We report a case of starvation ketoacidosis in a 60-year-old male with well-controlled diabetes mellitus type II following a strict ketogenic diet who then underwent prolonged fasting.

CONCLUSIONS: Although the ketogenic diet with or without periods of fasting might yield short-term weight loss, it has potentially dangerous side effects, including ketoacidosis. It is recommended that people, especially those with comorbidities such as diabetes mellitus type II, consult their physicians before initiating this diet. Clinicians must keep a broad differential when evaluating acute metabolic acidosis.

Keywords: Acidosis, Diet Fads, Diet, Carbohydrate-Restricted, Fasting, ketogenic diet, ketosis, Diabetes Mellitus, Type 2, Starvation, Syncope