Vin Diesel, well-known for his role in the Fast & Furious franchise, has been on a relentless fitness regime, driven by a determination to rival the physique of his co-star, Dwayne "The Rock" Johnson. The Hollywood heavyweight is preparing for the next installment, "Fast X," and keen to dispel any perception of falling behind in the physicality stakes.

Recent sightings of the 55-year-old actor at the Formula One Miami Grand Prix on May 5 showcased his renewed focus on fitness. Diesel, dressed in a sleeveless shirt, confidently displayed his enhanced muscles, seemingly basking in the attention of the spectators.

"Vin understands he may never reach Dwayne's level of muscularity or body definition, but he believes he can regain a robust physique that would be appealing to fans and also help him overcome his struggle with fluctuating weight," disclosed a source close to the actor.

Diesel, a couple of years back, had found himself in a physical low, grappling with unwanted weight gain. Since then, he has pledged not to return to that state.

The actor's dedication to his physical transformation has been extraordinary, involving strenuous weightlifting sessions, a diet loaded with protein shakes, pasta, and high-protein meals, and relentless determination to maintain the momentum. This intense regime has led to significant improvements, although the single-minded obsession with his physical state has raised eyebrows among his acquaintances.

One insider noted, "His return to the gym is commendable, but there are concerns about the level of his obsession with body image. It's simply not a good look for anyone."

The core of Diesel's commitment lies in his rivalry with Johnson and his fear of being seen as inferior. Moreover, Diesel's ego, matching his muscular ambition, doesn't permit him to slack off in his efforts for fear of being seen as less fit and being mocked for it. This deep-rooted concern continues to fuel Diesel's fitness fervor, even as onlookers voice their concerns over his borderline obsession.