"She had to lose thirty pounds if she wanted to stay in Hollywood," author Saul Austerlitz wrote in 'Generation Friends An Inside Look at the Show That Defined a Television Era'.
"Los Angeles was a tough place to be an actress -- it was a tough place to be a woman -- and Jennifer Aniston's agent was reluctantly levelling with her," the author added.
Aniston had gotten a call-back and was instructed to wear a leotard. According to 'Generation Friends', she joked, "This'll blow it for me," to her agent, who "responded seriously."
"Aniston was hardly fat -- everyone could see she was beautiful -- but as the show she would one day become indelibly associated with later made a point of noting, the camera added ten pounds," the author added in his book.
In a 1996 cover story for Rolling Stone, Aniston revealed her pre-fame guilty pleasure snack.
"I ate too many mayonnaise sandwiches. Mayonnaise on white bread --- the most delicious thing in the world," she revealed back then and said she didn't resent her agent for his potentially offensive feedback.
"My agent gave it to me straight. Nicest thing he ever did. The disgusting thing of Hollywood --- I wasn't getting lots of jobs 'cause I was too heavy'," she told the magazine at that time.
Years later, she told People that aside from the size, she was grateful that the moment prompted her to make healthier choices.
"I was like, 'What?!' But my diet was terrible, milkshakes and french fries with gravy. It was a good thing to start paying attention," she said with a laugh.
She shed the weight and soon landed her most famous role till date as Rachel Green in 'Friends'.
She had actually already committed to another pilot, 'Muddling Through', that got picked up by CBS.
NBC brass told the 'Friends' creatives to find another Rachel, but they had fallen for Aniston.
She shot the first six episodes of 'Friends' but was told she would be contractually obligated to drop out if 'Muddling Through' was greenlit. However 'Muddling Through' tanked and 'Friends' rose to fame, and Aniston became a celebrity nearly overnight.
Aniston recently told InStyle that she feels better than ever at the age of 50.
"Fifty was the first time I thought, 'Well, that number.' I don't know what it is because I don't feel any different. Things aren't shutting down in any way," she said.
"I feel physically incredible. So it's weird that it's all of a sudden getting telegraphed in a way that's like, 'You look amazing for your age.' I think we need to establish some etiquette around that dialogue and verbiage," she added.
On the work front, Aniston recently starred in the Netflix original movie 'Murder Mystery' alongside long-time friend and actor Adam Sandler. She will next appear in Apple drama series 'The Morning Show' and 'The Fixer', which is currently in pre-production. The movie is about a former Miss USA contestant who becomes a successful sports manager.