Forrest Whitley, baseball's consensus top pitching prospect, once followed Tim Lincecum's career the way a bloodhound chases a scent. He knew Lincecum's style, stats and sizzle. But there was one delicious bit of the Lincecum legend that had slipped past him.

The two-time Cy Young winner and perpetually skinny Lincecum revealed one spring that in an attempt to keep weight on, he regularly ordered three double-doubles, two fries and a chocolate-strawberry milkshake from his beloved In-N-Out Burger.

Lean and lithe in the Houston Astros' clubhouse this spring as he readies for an MLB debut that should come early this season, Whitley does a brief double take upon learning this double-double news. Then he nods confidently.

"I'd crush that," he says. "Everything is so small there. I'd crush that."

The road to the top for the game's No. 1 pitching prospect—according to both Baseball America and MLB Pipeline—is littered with fast-food wrappers, grease stains and a hunger for success that eventually drove him (mostly) right past the burger joints.

It was Whataburger for Whitley back home in his native San Antonio, and his standing order was a patty melt meal (Whatasize), a chocolate milkshake and six chicken tenders. He would put three chicken tenders on his burger and eat the other three separately. As he dined, he would dip the french fries in his shake. Sometimes, he would order an extra cheeseburger as a chaser.

"You'll never believe it," Whitley told Trent Thornton, a top pitching prospect in Toronto's system, as he described the enormity of that order when they roomed together last autumn while playing in the Arizona Fall League and living practically across the street from, believe it or not, a Whataburger.

"My God!" Thornton replied.

Whitley is a 6'7" right-hander, throws a fastball that touches 100 mph and once weighed 265 pounds.

He lost 70 of those en route to becoming the game's most mouthwatering pitching phenom.

Today, the fact that he once weighed 265 pounds does not seem that foreign to him.

"I can definitely believe it, and I could get back to that point very easily," he says. "I have the appetite of an animal. I could eat everything in sight if I wanted to.

"But obviously, I have to monitor that. I've put on a substantial amount of weight since last spring training. I'm up 30 pounds. I was at 195. I was skinny. Now I'm 225."

He laughs easily as he talks, his comments laced with a winning blend of self-deprecation and youthful vigor. He is friendly, earnest and authentic.

"He's a good dude," says Thornton, who was drafted by Houston in 2015, a year before Whitley, and then traded to the Blue Jays last November. "He's a character for sure. He's a really, really good pitcher who lives up to all the hype.

"He's a good teammate. He works hard."

Jeff Roberson/Associated Press

How Whitley changed his body and, almost certainly, his future is a testament to both hard work and self-discipline.

After his junior year of high school in 2015, he already was one of the best pitchers in his area and had become a magnet for professional scouts. But in the midst of all the glowing reports was one constant refrain: He was overweight for a schoolboy, especially his lower half, and had a bad body that could be a serious detriment to his future in baseball. As he read clipping after clipping, that's the part that stuck with him.

"So I made it a priority during the offseason to get fit, get in shape, get strong," he says. "Because I was fat, but I was also weak."

Um, yeah, that's...

"Bad combo," Whitley cracks, nodding vigorously.

So between his junior and senior year, he changed his ways. He lost weight and gained strength. He amped up his workouts. He slowed down on the burgers and leaned heavily on his mother, Laura.

"She started cooking super clean for me," Whitley says. "She made it super easy for me to eat as clean as possible. She was so great to me at that time. She still is, whenever I'm at home. Both of my parents are phenomenal cooks. She'd ask me what I want, and I'd just say, 'Surprise me.' They make such good food. They're so good. Really, really good."

As he focused on that clean eating regimen, what she cooked most frequently was chicken, green beans and mashed cauliflower, which, Forrest says, "my mom would make taste exactly like mashed potatoes. It was unreal. I couldn't tell the difference."

By February of his senior year, he estimates he had lost 60 pounds—dropping to 205. He then kept losing weight because he felt better and better. Friends would fail to recognize him. Soon, clothes failed to fit him.

"My mom was pretty pissed about that," he says. "I had to get all new clothes. I went from a 38 waist to a 32."

He entered his senior season of baseball in the best shape of his life, although he also admits to taking things a little too far.

"I've learned [since] you have to be at a certain percentage of body fat to be at your optimal performance in baseball," he says. "But at the time, I was ignorant. I didn't really know.

"I learned the hard way this year that being too lean can lead to a higher injury rate."

Aside from his fastball—which averages 94-96 mph when he's not reaching back for some extra cheese—he throws a cutter, a knee-buckling curve, a slider and a changeup. That he's polished beyond most other 21-year-olds makes the combination all the more lethal.

In fact, he started '17 in low Class A and was promoted to Double-A by season's end, becoming only the fifth schoolboy in the past 20 years to advance all the way to Double-A in his first full professional season. The others: Chad Billingsley, Zack Greinke, Clayton Kershaw and Dylan Bundy.

But just as he had in high school, he bumped into a few moments of learning the hard way that he hopes makes him wiser in the future.

The first was the shock of a 50-game suspension for violating the minor league drug prevention and treatment program that delayed the start of his 2018 season. Whitley has refused to publicly discuss the test, and the Astros will only say it is a private matter. Fox San Antonio's Chuck Miketinac reported Whitley attended an out-of-state college baseball game after the '17 season and that a friend gave him an "unknown stimulant" to help him stay awake on his long drive home.

"It's a learning lesson for him and for everyone," Astros manager A.J. Hinch says. "It's obviously a private matter. Not everybody knows details. But it's a reality, and if he uses it as a lesson moving forward of the potential risks of what you surround yourself with, then the program works as it should. And I expect him to do that."

Then, six starts into his delayed '18 campaign, he strained an oblique that not only sidelined him for a month but also knocked him out of the MLB Futures Game. He came back in August for two more starts before aggravating the oblique and missing more time.

This, he says, is where the learning also kicked in. Just as a young player must learn the correct time to deploy various pitches, he also must know his body. And what Whitley deciphered from the injuries last year is that he had gotten too lean. He's learned, he says, that the ideal body fat for him is somewhere between 12 and 15 percent and "I'm at 13.5 or 14 percent. I couldn't be in a better spot right now."

His spot this spring in the Astros clubhouse, lockering next to Wade Miley, Collin McHugh, Justin Verlander and Gerrit Cole, is perfect too.

"He's going to be a sponge," Hinch says.

Already this spring, he's been the butt of a classic camp prank. Upon returning from his suspension last June with four shutout innings while allowing only one hit and striking out five, Whitley celebrated with an Instagram post he captioned "Daddy's back."

The Astros noticed. From their visiting clubhouse in Arlington, Texas, that day, they attempted to razz him via text. But something got lost in the translation, and the texts were sent to the wrong phone number.

But on the first day of full-squad workouts this spring, the Astros hadn't forgotten Whitley's post. They gathered en masse in a clubhouse ceremony, and Verlander presented Whitley with an alternate version of his No. 68 Astros jersey: The name on the back read "Daddy."

"He threw me the alley-oop," Verlander quips. "I was just the one who got to put it down."

"You do that around the big leagues nowadays, you're probably going to have to wear it," Hinch says. "Literally."

"I think he should wear it every day," Cole says. "I think he should pitch a game in it is what I think he should do."

Whitley got a good laugh out of it, appreciated the thought put into it and plans to have all of his teammates sign the jersey and then frame it.

Whitley and Verlander, in fact, already have the beginnings of what could be a highly entertaining—let alone productive—relationship. Working out in Houston over the winter, Whitley threw a baseball 110 mph during a "pulldown" drill—a training method in which the pitcher gets off to a running start, stops, then crowhops as he throws the ball as hard as he can at a target 30 feet away. He tweeted it, only to see Verlander playfully respond:

In so many ways, Whitley is that energetic and irresistible puppy still growing into its paws. And at 6'7", harnessing all of his body's moving parts during his delivery probably will remain his biggest challenge as the Astros work to sand down his rough edges.

"Getting those all in sync is not the easiest thing to do," Whitley admits. "But you find it a lot easier to do when you have a good offseason workout plan. Getting everything in balance, symmetrical, it makes finding that center of gravity a lot easier."

Notice he said "gravity, not "gravy." He might be close to being all grown up now and on the precipice of MLB stardom, but his old eating habits remain the stuff of legend. Last autumn in their house in the Arizona Fall League, Thornton and J.B. Bukauskas, another top Astros pitching prospect, taunted him by pulling up his old photos on the internet and by dipping fries into their shakes from the Whataburger across the street.

Of course, with good friends and following his longest season, Whitley couldn't resist joining in. Especially with that Whataburger so close to their Arizona home.

"I wasn't good. I wasn't," he says. "I was bad in the Fall League. I was very bad. That's all right. That's what the offseason is for."

He stops for a moment, remembering the good times, good meals and the good-natured teasing. And he smiles.

"I'm glad this exists, man," he says of the lingering ribbing he still hears about his legendary eating exploits. "This is funny."

Scott Miller covers Major League Baseball as a national columnist for Bleacher Report. Follow Scott on Twitter and talk baseball.