(CNN) -- Matthew McConaughey wasn't the only "Dallas Buyers Club" actor pushing his body to the limit.
Co-star Jared Leto recently revealed to The Wrap that he lost 30 to 40 pounds for his role as a transsexual living with HIV in the 1980s.
To get down to 114 pounds, "I stopped eating," Leto said, adding that such a drastic physical change had an impact beyond the scale.
"It changes the way you walk, the way you sit, the way you think," the 41-year-old musician and actor said.
But Leto, who hasn't done a film in roughly four years, has altered his appearance for previous roles, including gaining weight to play Mark David Chapman in 2007's "Chapter 27."
As he told New York magazine's Vulture in 2012, "it's not about the most weight I can lose, it's more to represent the character."
While fasting to portray his "Dallas Buyers" character Rayon, Leto said he was meditating on "what it means to be a transsexual woman."
It looks like his hard work -- and that of co-stars McConaughey and Jennifer Garner, who portrays a physician -- paid off. "Dallas Buyers Club" received good reviews when it premiered over the weekend at the Toronto International Film Festival.
The film, based on a true story and directed by Jean-Marc Vallee ("The Young Victoria"; "C.R.A.Z.Y."), stars McConaughey as a homophobic, hell-raising cowboy who refuses to accept his doctors' warnings he only has 30 days to live after being diagnosed with HIV in the mid-'80s.
McConaughey lost 38 pounds to play the gaunt Woodroof, who went against the medical system and set off across international borders to round up HIV treatments. Using an entrepreneurial hustler's spirit, he then sells the treatments to those in need through his "Dallas Buyers Club."
The Hollywood Reporter called the film an "enthralling drama" told with "vigor and an assured light touch" and said the star's portrayal of Woodroof is "a full-bodied characterization that will take McConaughey's already impressive career regeneration several steps further."
The review praised Leto, too, calling him "simply wonderful ... in the showier supporting role."
Variety also commented how well McConaughey inhabited his character, saying that "any doubts that still exist" about the 43-year-old star's talent will be "permanently put to rest."
"But McConaughey's is not the only performance of note in this riveting and surprisingly relatable true story," Variety said, complimenting Leto for his "sensitive, considerate" characterization.
The industry trade predicted that "rave reviews for both actors should draw mainstream (audiences) to one of the year's most vital and deserving indie efforts."
Audiences will find out if Variety's correct when "Dallas Buyers Club" opens November 1.