Everyone noticed a slimmer MIRANDA LAMBERTat Wednesday's CMAs.  It even came up backstage . . . and she was gracious enough to NOT be insulted. 

She explained, quote, "I've been working out.  I just felt that I should get a little more healthy . . . maybe get ahead of the game.  I'm going to be 30 on Sunday.  I thought, maybe if I get ahead of it I won't have to work so hard later in life."  

Sounds like she dropped the weight by cutting back on the junk food.  She said, quote, "I didn't give up really a lot really.  Just Cheetos, mostly.  But I might have some tonight, just to celebrate."

photo credit: getty images