For your height, you are appropriately 10lbs underweight. Suggest eating 3 meals a day or 5-6 small meals a day. If your appetite wavers, then suggest drinking a nutrient dense drink, such as Ensure or milkshake (milk and ice cream blended) once a day for calories and protein. Thank you for your question.
We are working on this with our son, and here is what we worked out with his doctor.
He is eating his protein spread out frequently every few hours. He is functioning noticably better mentally now that we have changed his eating to do this. I think it is because he is so underweight that when he runs out of food to burn he is immediately burning lean tissue because he has no body fat, and this causes trouble mentally. He gets squirrly when he needs to eat otherwise. Does this feeling sound familiar to you?
We have also added probiotics and digestive enzymes to improve his nutrient absorption.
Doctor also suggested increasing oils and good fats to improve nutrient absorption and add calories. Too early to say if he is putting on weight yet, but he is doing well mentally and emotionally!