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It's Always Sunny's Rob McElhenney Reveals The Gross Diet He Kept For Fat Mac

Fat Mac Rob McElhenney It's Always Sunny In Philadelphia FXX

The creation of Fat Mac was a hilarious gag that It's Always Sunny In Philadelphia seemingly pulled on a whim for Season 6. However, making it happen was much more difficult than one might expect. Co-creator and Mac portrayer Rob McElhenney revealed he gained 60 pounds for the character's then-new look, with a diet that consisted of ice cream soup and cottage cheese. Not together though...we think.

Rob McElhenney said he'd originally tried to gain the weight a "healthy way," with chicken and rice and other weight-building foods. But when that proved too difficult and time-consuming, his nutritionist he could get the same gains form eating two Big Mac's a day. McElhenney added a few other things on top of that gluttonous meal plan.

So, then I had Krispy Kreme donuts. Every morning, I would eat four of those. . . . At a certain point, it's not that fun. By the afternoon, I was drinking ice cream. I would take ice cream, and I would put it out on the counter in the morning and then it would melt. And then I would put weight gainer into it, and I would drink that every day. So then I was drinking heavily. That was a great excuse to drink wine.

That calorically magnified method proved much more effective than Rob McElhenney's attempt to gain mass in the healthiest way possible. Note that his doctor told the actor there was no healthy way to gain that much weight. When McElhenney referenced Christian Bale's transformational weight gains between roles as a point of reference, his doc mentioned that he knew Bale's doctor, and in so many words, the medical pro let McElhenney know it wasn't healthy for Bale to do either.

Rob McElhenney's health may have been rapidly declining, but he was definitely packing on weight. Unfortunately, he told Dax Shepard (on his podcast Armchair Expert) that the weight didn't seem to be progressing fast enough to justify the storyline. McElhenney had three months to go before shooting and knew he had to go the extra mile to complete the "Fat Mac" transformation. Fortunately, he managed to find the answer in a certain dairy product.

I read that cottage cheese metabolizes really slowly in your stomach. If you eat cottage cheese, the last thing you want to do is eat it right before you go to bed because it metabolizes so slowly. So, I was like, 'That's what I have to do.' So, I started eating cottage cheese in the middle of the night. I would wake up at 2 a.m. and I would eat cottage cheese. And then one week later after that, I came in on a Monday, and for whatever reason, it was like I popped. . . . I went from about 160 to 220.

Fat Mac was there weight-wise, but was still not quite perfect perfect. Most of the weight to this point had only traveled to Rob McElhenney's gut, so he needed to find a way to get it to go elsewhere. He then enlisted a fitness trainer to help him with powerlifting so that the weight could be spread out to other parts of his body. McElhenney said it was a risky gambit, given his sudden weight gain, but it paid off.

For anyone wondering what effects were suffered health-wise, Rob McElhenney said he did gain a fatty liver, but that it went away once the weight dropped off and he stopped drinking as much. That played into losing the weight as well.

McElhenney said it was "easy" to drop the pounds after the Fat Mac season, mostly because quitting drinking cut out an average of 4,000 calories a day. The actor's tolerance for wine had gotten so high during the process that he said he could finish 1.5 to 2 bottles of wine a night.

Rob McElhenney did eventually get back in shape and then some in what became the premise for "Jacked Mac." McElhenney shared a photo of his two radically different It's Always Sunny In Philadelphia physiques on Instagram and shared the big secret to how he got to be so ripped.

Mac Rob McElhenney Instagram

With a plan that sounds so easy and available to everyone, it's a wonder we aren't all Jacked Macs, right?

It's Always Sunny In Philadelphia is in the offseason right now, but viewers can binge all seasons currently via FX+. For a list of shows that are airing or soon to air in the coming weeks, be sure to visit our fall and midseason premiere guides.

Mick Joest

Mick likes good television, but also reality television. He grew up on Star Wars, DC, Marvel, and pro wrestling and loves to discuss and dissect most of it. He’s been writing online for over a decade and never dreamed he’d be in the position he is today.