Hello, at 5-6 months it is normal for infants to double their birth weight. By the end of year one, they should triple their weight. It is not necessary to overfeed a baby. If I understand his age is only 6 months, then it is advised to begin solid foods. The first food group to try is cereal fortified with iron, such as rice cereal for babies. Try 1-2 tsps. mixed with breastmilk or formula to start with two to three times per day. All food should be pureed or a from a baby food company for his age. Next try a green vegetable such as peas or green beans pureed, each food is introduced every three days as tolerated. The last food group is usually meat, after fruits. In addition, it is best to avoid egg whites, citrus and berries until the baby is one year of age, especially if your family has a history of allergies. Please check with your pediatrics clinic to follow his weight and health.