Have run 11 marathons after Sept 2012 and gastric sleeve surgery. Used to weigh 322 lbs. Now weigh 190. Can eat anything I want as often as I want just not as much in one sitting. I don't think you need a special "diet" to run marathons after gastric sleeve surgery. I don't notice any difference when running and refueling after the surgery that I had. It has made life much easier.
I didn't run or workout for 13 yrs before having the surgery.