It is narrated from Sayyidah Aisha (may Allah be pleased with her) that when the Prophet Muhammad (peace and blessings be upon him) intended to eat something while in a state of janabah, he would wash both his hands and then eat.
Hadith Referenceصحيح ابن خزيمه / جماع أبواب فضول التطهير والاستحباب من غير إيجاب / 218