The idea itself was enough to give weak-stomached critics indigestion.

But Joe “McRunner” D’Amico proved hundreds of naysayers wrong Sunday, by completing the Los Angeles marathon in a personal best time after eating nothing but McDonald’s fast food for a month.

The Palatine dad’s time of 2 hours, 36 minutes and 13 seconds was 41 seconds faster than his previous record, and good enough for 29th place overall in the 26.2 mile race. . .