Ruth, 45, rose to fame with Gavin & Stacey. She lives in Cardiff with her husband David, where they run Tidy Productions, and she has three stepchildren. Ruth has written and stars in a new ten-part comedy drama, Stella, which starts on Sky1 in January.
Health is really important to me. My uncle had a stroke and died last year, which was a wake-up call. I made an effort to lose weight because I think the problems of obesity are becoming more known now. I was 17 and a half stone. I stopped drinking five years ago, and I stopped smoking around three years ago, so the weight was the next thing.
I've lost four and a half stone. The key thing was acceptance and patience – to accept it was going to take a couple of years. I wouldn't judge anyone on how they lose weight, but the only way I was going to do it was to count calories.
It was heartbreaking. There was literally a moment where I thought, "Oh my god, I've got to eat less food." I've still got a way to go and I'm in this half-stone zone that I don't move out of.
I used to hate going clothes shopping. I used to say if I could be a size 16, I'd be happy. I'm a size 16 now and it has opened up a whole new world because there are so many more shops that do bigger sizes now. I don't wear as much baggy stuff – I don't hide as much.
I think there's immense pressure put on women in the public eye. Being papped is frightening. I saw a photo of me early in the morning, on the way to a radio interview. It was one of those "How not to dress" columns, which was so embarrassing.
Stella came about because Stuart Murphy, who commissioned Gavin & Stacey, had this idea of me playing a British-type Roseanne. But this was the idea that I had. I like the idea of a woman who set out at the age of 16 with her life going in one direction, and was very determined about that. With that in mind, she was at technical college but then she got pregnant.
One of the other things that is central to Stella is friendship. Stella has this friendship with Paula, and they've known each other since school. I also have friends I've known since school, and there's something about those friendships. You've gone on journeys together, and when you were 16, you would never have imagined where you'd be all these years later.
My own friendships were the inspiration for the friendship between Stella and Paula. There's a bit in episode one where they go to the curry buffet and dance to Dexys Midnight Runners. That was the anthem for my friends and me in the 80s – we'd all get the hairbrushes out and sing along.
My friends aren't remotely bothered about me being on the telly, and neither are my stepkids. I love that. I find it really refreshing. We talk about what's going on in their lives, which is much more interesting.
My ideal night out is probably the cinema. We love Scotland if we can get a few days away - we love to go right up to the Highlands. We like walking.
When it comes to clothes, my indulgence is designer sunglasses, but what I really spend money on is skincare. I love a good facial and a good massage. I would do that over shopping any day. I don't get the designer handbag thing. I think it's mental, when you can get something that looks just as good from the high street.
Stella starts on Sky1 HD on Friday 6 January at 9pm
This is an edited version of Ruth's interview. To read the full article, pick up the February issue of woman&home, out now.