Katherine Heigl ''panicked'' about losing her pregnancy weight.

The 38-year-old actress gave birth to her son Joshua Jr. - whom she shares with her husband Joshua Kelley - in December last year, and after putting on ''50 pounds'' during her pregnancy, the star has now admitted that she worried she wouldn't be able to shed it all.

She shared: ''In the seven months since Joshua Jr was born I have managed to slowly but surely drop my pregnancy weight with only 10 pounds left to lose. I gained almost 50 pounds during my pregnancy and I'm not gonna lie, I had moments of sheer panic that I'd never be able to lose it all. I had hoped to only gain 25-30 pounds like my mother during her pregnancies but found that just wasn't possible for me.''

Katherine - who also has adopted daughters Naleigh, eight, and Adelaide, five, with her spouse whom she married in 2007 - originally tried to keep up a gruelling exercise programme whilst she was pregnant with her son, but said she ''gave up'' after four months as she wanted to ''trust [her] instincts''.

She said: ''Despite starting my gestation out on a pregnancy friendly meal plan and hiking my butt off 5 days a week my weight kept creeping up. At a certain point, probably around 4 months I gave up the struggle and tried instead to respect my body's needs and trust my instincts. About ten days after Joshua Jr's birth I got back on the scale to see where I was at and how far I had to go.''

But now the 'Knocked Up' star is well on her way to getting her pre-baby body back, she says the best way to lose weight is to get her mind in a positive place by giving herself a pep talk every morning.

Writing on her Heavenly Days blog, Katherine said: ''My best weight loss advice is to start every morning by saying out loud a positive mantra of your choice about your body. Mine is 'I am easily, with good health, inspiration, grace and gratitude losing weight faster than I can even imagine with harm to none.' Then I say my gratefuls. Thanking my body for its perfect health, strength, limberness, vibrancy, youthfulness and beauty.

''Whether I always believe these things about myself and my body or not, I say them. By saying them out loud with love and gratitude I have found that I not only start to believe them, but my body exhibits what I say and believe.''