Hello, We know how you feel as a father and we also appreciate your concern towards him. You have asked for Diet chart. Since you have requested for a best one then first we need his height and weight and what are his likings and non likings.since we have only limited information. We can suggest you with a suggestion that is consult s dietician. For appetite building in person who is on chemo would be a task anyhow let's try a old home remedy which is effective till today and that would be Luke warm water with a pinch if honey in the morning would help. Thank you