Dean, you definitely did the right thing not running. I went out for a long slow 13 miles a couple of years ago after building my mileage up but just didn't feel good, and after 2 miles i was really feeling crap. The legs were heavy, but i plodded on and completed the run, only to completely wipe myself out and then the next two weeks of my schedule were ruined.
A work colleague, and very good runner (10k pb 28mins!!) told me to forget the run if i felt like that. He said he'd experience it himself and stopped after a couple of miles on a marathon training run, turned around, and walked home.
Sometimes we just need to take a rest, and listen to our bodies, as others have said.
With the current mileage you're running the only difference it will make is you'll be rested and ready for your next run.
As far as the diet goes, its really down to you. Do you want to lose the weight or no? I'm around a stone over my fighting weight (lost 6lbs in the last month) and determined to succeed, which means i will.
Good luck.