Lawrence, who plays Katniss Everdeen in the movie, told The Sun that people considered her "too fat, too pretty and too blonde" for the part.
She said: "I didn't know until the interviewers told me that all the fans were p*ssed because I was blonde. Then I was like, 'What? Damn, I'll just dye my hair'.
"It was great to lose weight because it was unintentional. I didn't go to the gym once. It was just a really physical movie.
"I actually ate more on that movie than I ever have on any other because it was non-stop and physical and I needed energy. It happened very naturally with all the training.
"It was hard to keep weight on for continuity. I ate a ton. Any picture you see of me from that set, I'm probably eating."
The 21-year-old added: "It was intense. I had training about three times a day for a few months. Then, once we started working, I had to have the training just for endurance because it was so many hours.
"I mean, if there's a scene of me running up a mountain, that's what we shot all day - me running up a mountain. I had about six weeks of archery. It was brand new to me and I loved it. I think I'm good at shooting arrows now - and I can skin a squirrel!"
Opening at the weekend, The Hunger Games has already achieved the third-highest US opening weekend of all time behind The Dark Knight and Harry Potter and the Deathly Hallows - Part Two.
Watch Jennifer Lawrence talking to Digital Spy about The Hunger Games below:
