A budget question: How much is acceptable to spend on food?

Right now I am working on a realistic budget that will work for the two of us and our two dogs but I am unsure on what to aim for when it comes to setting an amount for food. Right now I know that we eat out waaaaaaaaay to much and we also spend more then we should at the grocery store as well. I would say on an average week we spend 50 dollars on eating out and 75 at the grocery store. Thinking of spending at least 500 dollars a month on food for two people gives me a headache. I am trying to lower our take out bill to 20 a week (one take out a week) for now hopefully lowering it as time goes on. What I am unsure of is how much to try and lower our grocery budget to? Since we are going to be eating out less I am tempted to keep it the same and try to lower it as the months go on but that seems like a cop out so I think I am going to shoot for 60 dollars a week with hopes of lowering it more as the months pass and I get better at this whole being thrifty thing. That will take us down to $320 a month (I tend to shop 4 times a month even if it  works out to be 5 weeks) with a savings of $180 dollars. Does this sound realistic or should I be aiming for even better savings? Making a budget I think we can stick to is harder than I thought!