Formula milk weight gain

Hi mummies. Does anybody know which brand of formula milk causes rapid weight gain and which doesn? I switched my son from breastmilk to NAN optipro and he gained almost 2kg in 2 weeks. The weight gain was quite insignificant for my daughter previously when we switched frm breastmilk to aptamil. #formulafed #formulamilk #advicepls Edit: my son is a month old