Our pediatrician said there was no reason to heat formula. We used powdered formula, just put it in a bottle with "cold" (i.e. unheated) tap water and shook it up right before feeding. Also great for traveling, you don't need a cooler/ice packs to keep mixed formula cool, just bring a bottle of water and mix with the powder as needed. Not storing formula in the bottles also means you don't need to sterilize bottles. Just wash them in the dishwasher and store them empty/dry. We never heated baby food in either, just opened the jar and fed it.