My 15 week old lost 1kg in a week

My daughter lost 1kg in 5 or 6 days, i think this is drastic but, i wonder if this can be normal?
She hasnt changed in her eating habits from 4-7 ounces 5-6 times a day shes been strictly on formula since 8 weeks old. I havent ruled out her activity, she is definitely more active the past 2 weeks holding herself up, rolling alot, she is awake no longer than usual which is about 8 hours a day max. Seems like alot for a baby to lose so fast.

[Renee Radenberg]

Both her weight and height are between the 90-75th percentile which is good. For her age she needs 4-6oz of infant formula or breast milk 6-8 times a day. Suggest increasing the amount of formula she drinks or increase the frequency so she does not lose weight.