It depends on how you claim your meals. I use the "simplified" method, meaning I claim a fixed rate for each day that I am on the road. There is a raging controversey on just
what that amount should be, but it has been my experience that the gov't does not find $50/day unreasonable. I also understand that this year the rate is going from 50% back to 80% of the allowable expenses will be used.
You can claim any expenses that you would encur on the road, for example if you have a cell phone, any maps you buy, the US exchange rate (which fortunately is pretty low now).
Hope this helps you.