Actor Jared Leto is the latest Hollywood star to gain weight for his leading role in CHAPTER 27 - about the murder of John Lennon.

The heart-throb, who has been linked romantically to such Hollywood beauties as Lindsay Lohan, Scarlett Johansson and Cameron Diaz, admits he found it very easy to pile on the pounds.

Leto says, "I've been eating burgers and fries from the Burger Joint (in New York City)."

The actor has gained 14 to 20 kilograms (30 to 45 pounds) to play Mark David Chapman, who killed the ex-beatle in 1980.

Along with his fast food diet, the former gym junkie has quit working out and has been hanging out in his apartment.