I had all-the-time morning sickness for the first 20 weeks, and some really weird cravings and aversions the whole pregancy. Often times the ONLY thing I could stomach was a Burger King whopper. (mind you, I was vegetarian before I got pregnant, so I didn't think I could even remember what a whopper tasted like).
Anyway, IMO, you do what 'ya gotta do to get your calories and protein. My diet improved as I moved through my pregnancy, but I ate some crap I would never normally eat (like Cheetos - and not much else - for an entire week???!!)