Say goodbye to meat and potatoes, the Big O - Oprah Winfrey's gone vegan with a vengeance!

The chatty fatty is not only signing in for a 21 day detox plan she's making three pals from HARPO take the oath with her.

Needless to say, the talk show titan will blog daily about every single pound loss .

"Don't know if I'm going to feel better or worse, but I'm willing to see if my body feels differently,"  Oprah blogged Day One.

It will  - just don't forget the colon blow, luv.