How do you fatten your baby up?
My baby had the viral flu recently and lost a lot of weight. Her paediatrician told me that she was underweight, for a baby almost 11 months old, Ania only weighed about 7kilos. Imagine my horror! I knew my baby was small but I didn't know that she weighed so less. I took suggestions from the doctor plus my mom and started making her daily meals more denser and richer with lots of carbs and fats. For example, you could try adding knobs of butter or teaspoons of ghee (clarified butter) to her lunch (rice, veggies, fish, meat, pulse, beans, etc.).
Also feed her starchy foods such as bread, noodles, rice, parathas, chapatis (indian breads). You can also feed the baby homemade vanilla puddings and custards, chocolate desserts and cakes. But do keep in mind that the baby gets its share of healthy foods such as lots of leafy greens (spinach both red and green), plenty of fish and fruits.
It's okay to try and increase your baby's weight but please do not go overboard, just maintain a healthy and standard weight according to its age.