How to help 4 years kid in gaining weight?

Calories: First be sure you've been in to your child's doctor for the annual checkup. Assuming there is nothing too alarming about the growth chart or the physical exam, the key is the calories. If your doctor agrees, you can boost intake by adding high quality fats in the diet, like salmon, avocado, use olive oil liberally, etc. Pediasure is a nutritional supplement in the form of a shake made for kids.