There are many things “It’s Always Sunny in Philadelphia” will be remembered for, but nothing quite as strange as Fat Mac. During Season 7 of the show, Mac transformed into a larger version of himself with his own distinct personality when Rob McElhenney — who writes for the series and plays the character — gained 50 pounds.
For McElhenney, adding on the weight was as much of a blast as one might dream. “It was so much fun, just as a project to change my body and eat whatever I wanted,” he says during the 2015 winter TV press tour. His experiment included a nearly 6,000-calorie-a-day diet that was monitored by a nutritionist, so it wasn’t entirely unhealthy.
However, McElhenney jokingly admits that while he wanted to gain even more weight, he decided not to based on advice from his doctor. Those 50 pounds paid off though, with Season 7 leaving fans many special moments to remember.
It even spawned the episode “How Mac Got Fat,” which gave the character a motivation for plumping up: He tried to get the physique of a bodybuilder and failed miserably. While he might have claimed to be simply “cultivating mass,” the gang repeatedly pointed out that was not the case.
Once the experiment was over, McElhenney returned to his regular diet and workout, regaining his former body shape. Still, the legend of Fat Mac lives on. While he may be gone for good, fans will never forget.
Perhaps co-stars Charlie Day or Glenn Howerton will be the next to pack on the pounds for “Always Sunny.” “If you look at the career of almost any actor, if we keep going it’s just going to happen naturally,” Day jokes during the winter press tour. “I think we’ll just bloat and bloat and bloat.”
If you forgot exactly how fat Mac got during Season 7, here’s a little look back to remind you.