Charisma has never been in short supply with Matthew McConaughey. But it was only when he married it with pathos and a deep commitment to his craft that he suddenly reinvented himself as a leading man who could ride that charm deep into awards season. He won his Best Actor Oscar for 2013's Dallas Buyers Club, a role for which he dropped nearly 50 pounds from his famously buff body to play the part of a heroic outlaw with HIV. His career has blossomed since what has become known, perhaps regrettably, as "the McConaissance." But that hasn't dampened his newfound dedication. For Gold, his new biopic of Kenny Wells, a paunchy, hapless mine owner searching for the big score, he packed on the pounds with pizza every night and milkshakes for breakfast, while maintaining the roguishness that has buoyed many of his characters. In fact, he found inspiration for the character in his own father. Here, he tells some of his favorite tales about Dad, and explains why Mom prefers the pre-McConaissance McConaughey.

How did Gold come to you?
It was sent my way about five, six, seven years ago.

Oh, really? Before Dallas Buyers Club?
I guess I'm exaggerating. I think four years ago, right after Dallas. Anyway, I got Gold and it's one of the three scripts that immediately when I read the character I was like, "I've got to play this guy. I don't think anybody else can do this." I saw him from the inside out and knew his spirit with the first read. And the only other two like that were Magic Mike and Dazed and Confused.

Because it reminded you of your dad?
I've been getting off to the idea that more truth can come out of an impression than what really happened. And this was an impression of my dad, but also people that he'd worked with back in the '80s. And I remember there was a time in the mid-'80s when the bottom had dropped out of the oil business and a lot of people owed my dad money. Everyone was going Chapter 11, Chapter 13, and my dad wouldn't go bankrupt. But we'd go try to collect money from people that owed him money, and he'd take me with him.

So here I am, 12, 13 years old. My dad's taking me to go see these people so we could shame them into paying him, right? But my dad loved shady deals. The whole family said he would much rather do a shady deal with some fun people than do a good deal with a bunch of straight asses. And he did these things. I mean, he would invest in diamond mines in Ecuador...

Really?
… and took my mom to Ecuador, and has this [picture] with the machete coming out of the jungle. There were no f--king diamonds there. It was a scam. This story I'm about to tell you is really the one that encapsulated who Kenny Wells was for me. It's Christmas Day, I'm about 16 years old. We're in southwest Houston. My dad says, "Let's go get some stocking stuffers," which means we're gonna go to K-Mart and get a bunch of nailclippers and, you know, Q-Tips and stuff.

Those are stocking stuffers? Q-Tips?
That's stocking stuffers. Stockings stuffers are big in the McConaughey household, whether it's cotton balls to nail clippers to whatever. So we head out. It's raining. It's a sleety, gray afternoon. He pulls off the highway about eight exits before the K-Mart we were headed to, and into this abandoned single-story strip mall. Broken glass, graffiti. We pull around back. There's dumpsters, fallen power lines, and there's a white van down there flashing his lights at us as soon as we arrive. My dad goes, "This is Chicago John." We pull up the car next to him. He leaves it running. He goes, "Stay here." He gets out.

I look out the window. This little guy gets out of the van. He's in a black leather jacket. He's bald. He's got a big pouch. He goes around the back of his van and he opens it up and there's f--king washing machine, a dish sink, candleholders. And he opens up a shoebox and pulls something out that's wrapped up in a bunch of paper towels. He walks around to the open door of his passenger van, backs into it. And my dad's facing him, so now my dad's back is to me, right? And I'm looking through the window and the guy opens whatever he opens. And this is what I see my dad's shoulders do. [Turns and hunches.] I hear him go, "Goddamn it," and he reaches in, pulls out his wallet, and I see this motion, counting off Benjamin Franklins for whatever is wrapped up in these paper towels.

He gets back in the car. He hands it to me. He goes, "Put it in the glove box, buddy, so nobody gets it." I don't know what it is. Is it a ferret? I don't know what the f--k it is. We drive. He doesn't say a word for about five minutes and I'm sitting there. What the hell's in the glove box? But I know something shady just went down. And he goes, "Open up the glove box, buddy. Make sure it's still there." I go open this thing up. I grab it. I put it in the middle console and I open it up. And he looks right and he goes, "Oh, goddamn, so that's a $22,000 titanium Rolex and I just got it for three grand. Goddamn!" That Rolex wasn't worth 500 bucks. It was a hot ass watch but that's the thing. My dad loved to deal like that.

And that was the spirit of Kenny Wells. He's one of those guys... there's a little poem we have in the movie, which is "bear with no feet sleeps in the wind." You know, that's it. So at the end if Kenny gets the money or if he doesn't, does it really matter? Would he change?

Did you do a lot of research on him or did you just do what you felt?
I did a lot. There was not a whole lot to learn. The guy's original name is David Walsh, and they did pull off this scam. He's dead now. He ended up [having a] heart attack or, you know, got speared by the end of a blunt object, is what I heard.

Oh, really?
He died in the Bahamas. Yeah, he was living in a sort of prison-mansion to keep people out from getting him. They pulled off a royal scam, he and Mike Acosta [played by Edgar Ramirez in the film].

You know what? I like you so much I was like, He was innocent.
Okay, because some people have said, "I like you so much I know you got away with it." [Laughs.] I mean, again, in Kenny Wells there were parts of my father and the people around him who had that insatiable appetite for life and everything. It was: "Yes, yes!" People were using their hands. They were physical. They got out of bed. I remember my dad would get out of bed, you know, throw his legs over the side and be like: "Today's gonna be the day, buddy. I'm gonna hit a lick." That was his line. "I'm gonna hit a lick."

"I'm gonna hit a lick." What's a lick?
It means: "I'm gonna get the big sell." "I'm gonna make something happen." And it didn't really ever happen all the way until the time that he moved on. It never really happened but that's the Kenny Wells-es, and there's a lot of them. These are people who never took the front door entrance to the American Dream. They were gonna con, finagle, and hoot-scoot their way in the side door.

And it prepared you for Hollywood. [Laughs.]
Yeah, sure. I come from a line of salesmen, and that was my dad and a lot of people. So I did the research on David Walsh but little things—like impressions of my father and those people that he introduced me to—that was what really helped the spirit of Kenny Wells take flight.

Do you think your father would've liked Kenny Wells as a person?
Oh hell, yeah. Yeah, yeah, yeah, yeah, yeah. And my brother. My whole family misses me being fat like that.

You were never fat like that.
No, I never was. For the film, though, getting up to 217 pounds, my nickname was Captain Fun because I was "yes" to everything. Pizza night was four nights a week. Milkshakes for breakfast were a great idea. You want beer? Yeah! It's 10 AM. I didn't tell my brother anything. But when I came back and saw him right before I went to shoot, he got like tears in his eyes: "It's Pop. You're Pop," which is what we called our dad. He's like, "Look, just the way you're wobbling. You're not on balance." Yes, I know my dad would dig it.

It's an intense thing to gain and then lose that weight. Was it a big decision?
It's hard to say which came first. The real David Walsh, he was more that size. But also these people, my father and these other people had that girth; they were full-bodied. I kind of happened alternate. I mean, I started getting into Kenny Wells and all the sudden looked down and was like, I'm up to about 200. When did that happen? And so I wasn't thinking about it. I was just living like Kenny and having a great time. I was like, Let it ride. And they pulled the fat suit out and I was like, "I don't think we're gonna need that." [Laughs.] I’m well on my way.

Was it hard to lose it after all that?
Yeah. You know, it's the same with gaining it back. It's like there's a holdup at the decades—meaning I was 217, got down to 211, and then hung there for 10 days. Can't lose another pound. Soon as I get to 209, vroom, easy. One week you're down to 201. Then you hang up at 201 for two weeks, get to 199, then fly to 191 and then hang up for two weeks…

Did your kids freak out seeing you so different?
No, it was gradual. Like I said, they thought I was Captain Fun in the household, you know.

[Laughs.] There was more of you to love.
Yes, definitely.

Did your father ever give you any advice? Or Mom, for that matter.
I mean, Mom had great stuff in the morning if you showed up. If you were not showing gratitude for the fact that you had a bed to sleep in she'd slap the table and send you back to your room. And all the way as you're walking back to your room she's saying, "You'll come out of that bedroom and come to this table until you're gonna see the rose in the vase instead of the dust on the table!" That was always her go-to.

The other thing—you'll love this one—is you were not allowed to gripe about anything. She was like, "You know what you sound like? You sound like the kid bitching about having no shoes. Well, let me introduce you to the kid with no feet, son." "Oh, sh-t. I'm sorry. You're right, Mom." [Laughs.] It was a really good one. Dad's deal was: "Don't lie and don't say 'can't.'" I think I got my first ass-whupping for saying "can't". The cuss words in our family were "can't" and "hate."

Your father died before your career really started going, right?
He died six days into my first acting job, on Dazed and Confused. I've always felt there's a bit of serendipity to that because everything before acting was a fad—you know, 18 and talking him into getting me the skateboard and the knee pads and the helmet. But for the first six days he was alive and saw me doing what ended up being a career.

And does your mom get protective? Did she get it when you changed up your career?
Yeah, she's 84 now. Still stays up an hour later than me every night and gets up an hour earlier; never been able to keep up with her. For us, it was not like, "That was then, this is now." Us McConaugheys... she would never look at it like that. Life's a long adventure. She liked the romantic comedies. You know, when she saw me in Gold, she's like, "What'd you do to yourself? Oh god! Matthew, what are you doing?" And when I got really skinny for Dallas Buyers Club, she didn't quite get it. [Laughs.] She was like, "Stop. Enough's enough. Are you sick? You look really sick. Enough, Matthew. Stop it!" I don't know. She probably liked me a little more with that look. She's been wanting me to put on weight since Dallas. Whatever it is, four years later I've kind of settled back into where I was before. She likes to see me with a little meat on my bones.