My baby is 4 months old. Her weight is 5.5 kg. She is gaining weight 600g to 900g in monthly weight check but she doesn't look chubby looking little lean type. Why like this

A. Yea rite. in the first 3 months, babies put on about 800-900grams each month. From 3-6 months, weight gain reduces to 1/2 kg/month. from 6-9 months, it becomes 1/3, and for 9-12 months, it becomes 1/4 kg. the birth weight doubles in the 4th month and triples when they reach 12 months of age.