I agree about breast feeding directly will spent alot of energy,at the begining I pump out the milk and feed them, and if not enough,i will feed a bit milk power, they grow up very will and meet the 90% of the grow rate,however, dr. said they are too fat,can no milk power. Then,I try feed on demand and hope will have more milk,but i found it is less milk and babies are getting skinner and skinner. Now, they already 13months,but still around 9kg, I think must be careful to consider.