Behati Prinsloo has already lost "a big chunk" of her baby weight.
The Victoria's Secret Angel only welcomed her and Adam Levine's daughter Dusty Rose last week but has reportedly slimmed right down already.
A source said: "Behati is breastfeeding and lost a big chunk of her weight when she had the baby.
"The weight gain was mainly in her belly during the pregnancy. She's taking it easy but likely go back to working out once Dusty is more settled."
And the happy couple are thrilled by their new arrival and are "completely attached" to their little girl.
An insider added to E! News: "Behati and Adam are home with Dusty and they are completely attached to her. Family and close friends come over to see Dusty. Behati loves being a mom and can't wait to eventually expand the family more ... They both don't want to leave Dusty out of their sight. Dusty is a happy baby."
Meanwhile, the Maroon 5 singer previously spoke of his excitement at becoming a dad.
He said at the time: "It's awesome. I'm going to be a dad. S**t, I'm excited. I'm going to be a f***ing dad. I'm going to spoil Behati ... Kid's not even out yet. Can't be spoiling a kid before a kid gets out ...
"I'm ready to be a dad. You're born to be a parent, that's what we're here for, really. All the other s**t is great, but it's not what we're here for."