You can come out way ahead on per diem if you are smart and do a little planning. 90% of the time you get free breakfast at hotel. Lunch can usually be free via something you grabbed from breakfast or out of the flight snack basket or pack a few PB&J's for your trip so I rarely paid for lunch either. I will splurge for a nice dinner if the layover permits and I almost always have $200 leftover per diem each month.