The reality star is five months pregnant but has not started wearing maternity clothes.
She told US Weekly: "I'm so skinny that I can wear larges or extra larges. I only just bumped up to a medium.
"I'm five months and you can't really see anything. It's gonna pop up in like a week."
When Jessica Simpson was mentioned, Snooki laughed and added: "I would die if I were her size."
She continued: "She said she indulged in everything that she wanted. I'm trying to eat healthy - fruits, lots of jelly and Italian ices. Nothing fattening at all."
The 24-year-old and fiancé Jionni LaValle announced in March that they are expecting a child.
Snooki recently told People magazine that pregnancy has made her "more mature".