You don’t necessarily need to double your grocery bill, but you are going to have to eat more. I am a grad student with a family and I managed to get the groceries to feed well. I just can’t afford the more expensive organic foods. Buy some egg whites. Drink some milk. Fresh vegetables are cheap and healthy. Oats don’t cost much. Canned meats work if you don’t have much cash. As far as time goes, spend some time on Sunday pre-planning and preparing your lunches.