The White Collar actress told People that her diet has suffered since she found out she is expecting.
"I was a vegetarian for many, many, many years and all of a sudden I started to crave red meat," she said at a USA Network and Vanity Fair bash in New York.
"Crazy enough, I had a steak before I left tonight and I would never have eaten one before. One day I just woke up and craved meat."
Thiessen, who is expected to give birth in three months, added that she also enjoys foot rubs from husband Bradley Smith.
"He rubs my feet, my shoulders and he always gets anything for me even if I'm all hormonal. I have the best husband and he's a sweetheart."