Singer Jessica Simpson is happier than ever before after losing a little over 20kg.

Simpson, due to marry her fiance Eric Johnson this year, said that she had lost confidence after she gained weight post her first pregnancy.

She plans to stay fit for her wedding day.

"I think it's about time! Knowing that I have the wedding coming up is an incentive to stay on Weight Watchers, count my points and stay in the gym. I mean, when you see my dress, you'll know," she told people.com.

Thanks to weight loss classes Weight Watchers, she is gettting back into shape.

"When I started Weight Watchers, I didn't know what to expect at the meetings but I really love going, I do. It reminds me we don't have to do this alone. It's so much better to have some back up and to do it together because we all face similar challenges," Simpson has said in a new ad for weight loss classes.

"The meetings keep me focussed and motivated and I have a new found determination that I'm really proud of. I can honestly say I've never been happier," she added.

Simpson has a 22-month-old daughter Maxwell and an eight-month-old son Ace.