 A computer program such as <unk> may be used to help generate recipes . The meals often have four components : heavy whipping cream , a protein @-@ rich food ( typically meat ) , a fruit or vegetable and a fat such as butter , vegetable oil or mayonnaise . Only low @-@ carbohydrate fruits and vegetables are allowed , which excludes bananas , potatoes , peas and corn . Suitable fruits are divided into two groups based on the amount of carbohydrate they contain , and vegetables are similarly divided into two groups . Foods within each of these four groups may be freely substituted to allow for variation without needing to recalculate portion sizes . For example , cooked broccoli , Brussels sprouts , cauliflower and green beans are all equivalent . Fresh , canned or frozen foods are equivalent , but raw and cooked vegetables differ , and processed foods are an additional complication . Parents are required to be precise when measuring food quantities on an electronic scale accurate to 1 g . The child must eat the whole meal and cannot have extra portions ; any snacks must be incorporated into the meal plan . A small amount of MCT oil may be used to help with constipation or to increase ketosis . 
