According to The Sun, the Your Body singer claims she was warned her career would suffer if she didn't slim down after piling on the pounds in 2002 - leaving the star at her lightest by 2006.
Xtina is quoted by the newspaper as telling Billboard: "During the promotion of my album Stripped, I got tired of being a skinny, white girl. I am Ecuadorian but people felt so safe passing me off as a skinny, blue-eyed white girl.
“The next time my label saw me, I was heavier, darker and full of piercings! Let me tell you, that wasn't an easy pill for them to swallow.
“I had gained about 15 pounds during promotion and during my Stripped tour. They called this serious emergency meeting about how there was a lot of backlash about my weight."
She continued: "Basically, they told me I would affect a lot of people if I gained weight - the production, musical directors. (They claimed) people I toured with would also miss out if I gained weight because I would sell no records or tickets for my shows.
“I was young, so I lost the weight quickly and was toothpick thin during Back to Basics promos and touring.”
The Voice USA star went on to add that while working on new album Lotus, she hit back at record bosses stating: “I told them, ‘You are working with a fat girl. Know it now and get over it.’
“They need a reminder sometimes that I don't belong to them. It's my body. My body can't put anyone in jeopardy of not making money anymore - my body is just not on the table that way anymore.”
Aguilera's claims come after fellow popstar Lady GaGa slammed those who criticised her weight, posting a series of underwear snaps online to prove she's "proud at any size."