The country singer grew up on a farm with lots of animals and decided when she was just 13 she didn't want to feast on meat because she couldn't stand the thought of the animals being killed.
She said: "I'm a vegetarian because I love animals. I grew up on a farm and they were all my pets! So the thought of me or someone else eating my pets kind of freaked me out at a young age."
Carrie admits she is obsessed with staying healthy because she wants to live a long and healthy life and is paranoid about damaging her body with bad food.
She added to the new issue of Women's Health magazine: "I'm the most normal person in the universe, but I'm very health conscious. I love working out. I love taking care of myself. We only have one body apiece and it's going to expire sometime, and I'm going to make sure it's a long, long time from now."
The 27-year-old actress has twice been named the World's Sexiest Vegetarian by PETA and is such an ardent supporter of animal rights she once said: "If you told me I could never sing again, I'd say that was horrible, but it's not my life. If you told me I could never be around animals again, I would just die."