The 44-year-old singer, from St Andrews, Scotland, shot to fame in 2004 with her song Black Horse and the Cherry Tree, and has achieved remarkable success since. She will be performing an intimate show at the Soma Festival in Castlewellan tomorrow .
Do you take regular exercise and if so, what?
The only regular exercise I do is playing my shows, which are basically two hours of aerobics. I've being playing big knees-up festival sets recently and although the Soma Festival gig will be an intimate one, I can still make a racket on my own.
What is the worst illness you've had?
Up until about seven years ago, I suffered daily with a chronic illness that infected my kidneys. In 2007 I was admitted into hospital - it was that bad. I went for an ultrasound scan and it turns out that an infection I'd had when I was a kid left me with a 'wee kiddy' kidney.
How healthy is your diet?
Mostly very healthy. I follow the Bulletproof diet - it is based on grass-fed steak, vegetables, no carbs and a lot of butter. I feel the best I've ever felt.
The diet is so good that I haven't had to join the gym obsessives in LA to keep my body toned.
I do a bit of yoga but I swear that, eating this way, I don't need to exercise.
Any bad habits?
When I'm on my cheat day from the Bulletproof diet, I could definitely go for fried food - yeah I'll go for that!
Do you drink and smoke and, if so, how much?
I don't smoke anymore and only drink very occasionally these days.
Do you take any supplements?
On a regular basis I take all the vitamins, plus turmeric, and I regularly use Epsom salts in my baths.
How do you take time out?
I literally stay at home and do absolutely nothing, just potter about and don't get dressed. If I do go out, I love going to the movies. If I have a few days, I get myself out into nature.
I've got my roots in Northern Ireland - my biological father's side of the family were from Belfast.
I'd like to see more of Northern Ireland. I'd like to get a camper van and drive all around.
This business is definitely very hard work and you can't do it in halves, it's a 24/7 job.
I find as I get older it's important to ask: am I healthy, how is my wellbeing, how are my relationships? Because the music could fall away at any time and then what would I have left? You have to have a life outside of it.
How well do you sleep?
Pretty well, although my schedule means I often don't get enough. I take a while to go to sleep and I'm naturally a night owl, so will often not get to sleep before 2am.
Do you worry about getting old?
Not at all. But I do want to aim for being a healthy and active older human.
What is your go-to product that keeps you feeling healthy?
Organic, grass-fed butter. Following the Bulletproof diet, which is a tweaked version of Keto, has totally revolutionised how I feel and look. It really is all about the butter!