It was recently suggested that the former Friends star is a fan of the eating plan - created by Tracy Anderson - which advocates consuming pureed baby food throughout the day followed by a sensible dinner.
However, speaking to People magazine, the actress denied the rumours and joked that "the last time I had baby food, I believe I was one".
She added: "I've been asked lately, 'Jen, what's this baby food diet all about?' I kept thinking, 'That's the strangest question ever'."
Biggest Loser trainer Jillian Michaels recently namechecked Aniston as having one of the healthiest bodies in Hollywood, suggesting that she looks like she "takes good care" of herself.
It was recently alleged that Aniston had increased her diet and exercise regime ahead of shooting her new comedy Just Go With It and had flown her personal trainer to the movie's set in Hawaii.