Melissa McCarthy has lost 45 pounds.

The 'Identity Thief' star has reportedly been following a new diet and fitness regime in a bid to improve her health for the sake of her daughters, Vivian, seven, and Georgette, four, with husband Ben Falcone, 41.

A source close to the actress said: ''She's been making small changes and seeing big results. It's given her a real confidence boost.

''She has been on a high protein, low carb diet.''

But the 44-year-old actress has no desire to shed too much weight, as she wants to maintain her curves.

The insider also told Star magazine: ''Melissa knows that fans love her big and beautiful, and she's not obsessed with dieting. She's looking for a happy medium.

''Melissa realised she wasn't being as healthy as she could be. She wants to set a good example for her kids and she wants to be around to become a grandmother too.''

The former 'Gilmore Girls' star previously insisted she didn't feel any pressure about her appearance in Hollywood.

Earlier this year, she said: ''I've never felt like I needed to change. I've always thought, 'If you want somebody different, pick somebody else.'''