This is a single-site, open-label, phase II trial of C7, a food supplement or medical food, for the development of treatment outcome measures for glucose transporter type I deficiency (G1D). The primary outcome measures are: 1. Safety and tolerability of C7 as measured by changes in comprehensive blood work, including lipid and free fatty acid panels, self-reported side effects and clinical exam; 2. Changes in brain metabolic rate by MRI and EEG measurements during C7 treatment; and 3. Maintenance of ketosis in G1D patients on ketogenic diet, as measured by serial ketone levels during treatment initiation.