The modified Atkins diet (MAD) has been shown to be effective in treating children and adults with medically resistant seizures. A recent study in children showed that the use of KetoCal® once per day in addition to the MAD appeared to be beneficial when used during the first month. The investigators hypothesize that including a daily KetoCal® liquid tetrapak with one meal during the initial month of the MAD will produce urinary ketosis in more adult patients than the MAD alone and will lead to greater seizure reduction.

Inclusion Criteria:

• Adults ages >17 years.
• At least weekly seizures (or 4 per month). All seizure types allowed.
• Tried at least two anticonvulsants.

Exclusion Criteria:

• Unwilling to restrict carbohydrates
• Significantly underweight (Body Mass Index <18.5)
• Prior use of the modified Atkins diet for ≥ 2 days
• Prior use of KetoCal® at any time for any duration
• Use of the ketogenic diet within the past year
• Kidney disease
• History of hypercholesterolemia (total cholesterol > 300 mg/dl) or hypertriglyceridemia (triglycerides > 200 mg/dl)
• Metabolic or mitochondrial disorder
• Pregnancy or breastfeeding
• Lactose intolerance or milk allergy
• Aversion to liquids or inability to eat solid food