A 3-year-old boy from rural Maharashtra presents with recurrent episodes of hypoglycemia, hepatomegaly, and developmental delay. Investigations show elevated plasma acylcarnitines, reduced ketone bodies despite fasting, and normal blood ammonia. Urine organic acids reveal dicarboxylic aciduria. A diagnosis of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is suspected. What is the most appropriate immediate management step?