When the first official image of David Corenswet in the Superman suit was released, the internet didn’t just notice the costume—they noticed the frame filling it. For an actor previously known for his slender, “preppy” physique in Ryan Murphy’s The Politician, the transformation was jarring. Corenswet hadn’t just “toned up”; he had undergone a radical physiological overhaul. To prepare for the 2025 Superman reboot, Corenswet added nearly 45 pounds of mass, transitioning from a lean 195 pounds to a peak weight of 240 pounds.
This was not a transformation achieved through “magic” Hollywood shortcuts. It was the result of a scientific approach to hypertrophy, a massive caloric surplus, and the expert guidance of celebrity trainer Paolo Mascitti.
The Architect of the Physique: Paolo Mascitti’s Philosophy
To build the “Man of Tomorrow,” James Gunn enlisted Paolo Mascitti, a trainer known for his work with stars like Glen Powell and Jacob Elordi. Mascitti’s philosophy for Corenswet was simple but punishing: Master the Basics.
While many “superhero workouts” rely on flashy, complex movements for the camera, Mascitti focused Corenswet on “The Big Ones”—compound movements that recruit multiple muscle groups and stimulate maximum hormone response. The goal wasn’t just to look like a bodybuilder; it was to look like a “farm boy” from Kansas who happened to have the strength of a god. This meant prioritizing density and functional power over just superficial definition.
The Training Split: Push, Pull, Legs
Corenswet’s routine followed a classic Push-Pull-Legs (PPL) split. This allowed him to hit every muscle group with high frequency while allowing for adequate recovery.
- Push Day: Focused on the chest, shoulders, and triceps. Exercises included the Incline Dumbbell Press (to build that “superhero” upper chest), Seated Overhead Presses, and Cable Flyes.
- Pull Day: Dedicated to the back and biceps. Heavy Rows, Pull-ups, and Lat Pulldowns were staples to create the “V-taper” silhouette.
- Leg Day: This was Corenswet’s “Kryptonite.” Despite his 6’4″ frame, he committed to heavy Squats and Walking Lunges. Mascitti noted that while Corenswet loathed lunges, he never skipped them, understanding that Superman’s power comes from a solid foundation.
Corenswet trained for approximately two hours a day, three to four times a week, during the most intense phases of his bulk. On off days, he focused on active recovery and wire training—a core-intensive practice used to simulate flight on set.
The “6,000 Calorie” Challenge: Eating to Grow
The most difficult part of David Corenswet transformation wasn’t the iron; it was the plate. Being naturally ectomorphic (lean), his metabolism burned through fuel faster than he could consume it. To combat this, Corenswet had to enter a massive caloric surplus, reportedly consuming between 4,500 and 6,000 calories per day.
His diet was meticulously balanced:
- Protein (30%): Sourced from whole eggs, chicken thighs, ribeye steak, and whey protein to repair muscle tissue.
- Carbohydrates (50%): Essential for fueling two-hour workouts. This included massive amounts of white rice, oatmeal, and sweet potatoes.
- Fats (20%): Healthy fats from avocados, nuts, and olive oil to support hormonal health.
One of the more humanizing aspects of his journey was his “cheat” food. Mascitti famously caught Corenswet eating cereal during remote FaceTime check-ins. When questioned, Corenswet’s defense was classic Clark Kent: “What’s wrong with cereal?” This balanced approach prevented burnout and allowed him to sustain the high-calorie intake for five months.
The Struggles of the Bulk: “I Didn’t Fit Into My Pants”
Gaining 40+ pounds in a matter of months comes with a physical and mental toll. Corenswet has been candid about the fact that at his peak weight of 238–240 pounds, he “didn’t feel great.” The sudden weight gain made him feel sluggish and, quite literally, “claustrophobic.”
By the time he arrived for his first costume fitting, he had outgrown the initial measurements taken during his screen test. The “S” shield on his chest was stretched to its limit, and he joked that he had gone from a size Medium to a 2XL in some brands.
However, once filming began, the “bulk” naturally transitioned into a “cut.” The physical demands of shooting 12-hour days—often in a heavy, non-breathable suit—caused him to drop back down to a more sustainable 225–230 pounds. This “filming weight” is where the definition and “hardness” of his muscles became most apparent on camera.
The “Natty” Debate and Mental Fortitude
In the modern fitness era, any rapid transformation is met with skepticism regarding Performance Enhancing Drugs (PEDs). Corenswet, however, has been emphatic about his “natty” (natural) status. He credits his results to three non-negotiables: Extreme Calories, Heavy Lifting, and Massive Sleep.
Corenswet told reporters he would often go to the gym, come home and pass out for two hours, and then sleep another nine hours at night. This level of recovery is often the “missing ingredient” for average gym-goers. His body was a full-time job.
Why the Transformation Matters
A Superman who looks “too” lean can feel fragile; a Superman who is “too” shredded can feel like a gym rat. Corenswet and Mascitti aimed for a “heavy-weight” look—broad, thick, and powerful. It’s a physique that commands respect and provides a visual shorthand for the character’s invulnerability.
As Corenswet steps into the light as the centerpiece of the new DCU, his physical journey serves as a testament to his dedication. He didn’t just want to play the part; he wanted to inhabit it. The sweat equity he put into the squat rack and the thousands of calories he forced down were all in service of one goal: giving the world a Superman they can believe in.
