Why Sylvester Stallone's Rocky 3 Diet Was So "Dangerous"

screenrant.com:

Sylvester Stallone got into incredible shape for Rocky 3, but here's why he later called his diet for the sequel "very dangerous." Like the titular boxer, Rocky itself was a major underdog story in the movie business. Before Rocky, Stallone had appeared in small roles in Woody Allen or Robert Mitchem movies and went on to bigger parts in low-budget projects like Death Race 2000. Rocky was his screenplay, but despite receiving major money offers to sell it so bigger names like Burt Reynolds could star, he insisted only he could play the lead. Rocky was thus assigned a small budget, but it went on to become a major critical and commercial success.

Rocky made Stallone's career and set the blueprint for «underdog» sports movies like The Karate Kid — which was also helmed by Rocky's John G. Avildsen. Stallone would later helm the second and third Rocky movies, where the success of the title character also mirrored the star's own rise to fame. While he was obviously in very good shape during the first two Rockys, Stallone would increasingly focus on sculpting impressive physiques for himself during the '80s. In addition to helping characters such as Rambo appear later than life, this focus on looking impressive physically is likely due to his rivalry with the equally muscle-bound Arnold Schwarzenegger during this era.

Related: Rocky's Movie Rights Ownership & Controversy Explained

Even in his later work like 2010's The Expendables, Stallone made his physique part of the character. The star once revealed in an Instagram post (via Men's Health) in 2017 that to achieve his ripped look for Rocky 3 — which changed the franchise in many ways — he undertook a "very high protein" diet which consisted of small portions of oatmeal