How can my child gain weight

Yes my son is 12 years old and 4 feet tall and weighs only 62 lbs. How can I get him to gain weight fast if possible?

[Renee Radenberg]

His weight and height is below the 5th percentile for his age. Even though they are both below the 5th percentile, they are in proportion. He may be small in stature due to genetics; however, he is on the start of entering puberty and will be having a growth surge into his early 20's. Suggest Carnation Instant Breakfast, as a milk shake, which is the cheapest for extra calories and protein for weight gain. You can make your own milkshakes (ice cream, fresh fruit or frozen fruit, milk blended together) or yogurt smoothies (yogurt, ice cream, and frozen fruit). He should eat 3 meals a day with snacks between meals too.