Many times at jobs I've had I have had bosses who expect me to work through my lunch hours. How do you feel about this? Do you do it or not?I will work the occasional lunch hour if I can see the necessity for it but if it becomes a habit I put my foot down and say sorry I have an appointment that I can't cancel. Or I tell them I have plans for lunch.
You don't get paid to work your lunch hours and if you continually do it you will be forever expected to do it.
Everyone needs a break away from the office even if you just go for a walk outside for fresh air.
So don't let your bosses take advantage of you. If it requires you do this every day then it means that he does not handle his time well and needs to hire someone else to handle the overtime or he needs to pay for your overtime.
See the reason they ask at lunch is cause then they can say they don't keep you for any overtime cause you get to leave on time and they don't have to pay you.
So be up front and tell him that you expect something in return.