Answer: Is normal
Explanation: Antonia shouldn't be concern at all, babies with that age ( 8 months) are expected to put on alot of weight (become chubby). If a baby isn't gaining weight or is lossing weight at 8 months old, there might be a health or nutritional related issue behind that.
Babies are expected to gain wait fast and after certain period of time, they stop and might even loss some weight as they get taller (growth).