You’ve just turned 60; does that bother you?
A bit. It’s hard to move on from this birthday because you fill in the forms for your pension and realise most people in this group no longer want to work, or aren’t able to. I can’t think of anything worse than that.

Floral leotards still your favourite get-up?
Not any more, but I still wear Lycra leggings with short, fitted T-shirts.

Are you as fit as you were at 30?
More so. I teach two aerobic classes every week in Leicester. Some of my ladies have been coming to me for 25 years. Then I’ll do another workout during the week. The rest of the time I’m just chasing about being busy.

Is it true that you can’t run?
After a couple of hundred metres I’d struggle to get my breath.

But how come, if you’re as fit as you claim?
It’s partly because I have asthma, partly because I’m not used to it. I could train to run better but I don’t want to. I don’t like running.

Has asthma held you back?
I’ve had it since I was 2, so I’ve got used to it. I can do aerobics all day without any trouble. The medication has improved enormously; steroid inhalers are very effective.

Always have one tucked into your leggings?
I always have it with me, yes. It’s probably more a psychological thing.

Tried anything alternative?
Because my asthma has been dealt with satisfactorily by medication, I haven’t had the inclination. I had a blood test once which suggested that I shouldn’t eat dairy produce, sugar and wheat, but I wasn’t prepared to make those changes.

A natural sceptic?
I wouldn’t pooh-pooh it, but I have considerable faith in conventional medicine, so it has never been a priority.

Does your 47-year-old husband provide an incentive to stay slim?
He’d hate me to be overweight. It’s a tall order to expect that by staying slim I can look his age, but it makes it less obvious that I’m older when people see us together.

Ever tempted to throw out the scales and enjoy life?
I might at 80. At the moment I like being able to wear size 8 clothes. The other big incentive is to avoid putting extra pressure on my joints as I get older. If I put on weight, I suspect my knees would hurt.

Are you addicted to being slim?
I’ve reached the point of being detached from food; I see it as fuel. I can be halfway through a meal and think “I’ve had enough now”. It’s taken me a long time to get to this position.

Not one of life’s greatest pleasures, then?
I’m very pleased that it isn’t. The best thing about getting older is that your appetite gets smaller.

Do you cook at home?
Oh yes, it’s much better than eating out because people always watch what I eat in restaurants. Sometimes I want chips. But even if no one is looking, the kitchen staff will say: “Oh look, Rosemary Conley’s ordered chips!”

Aren’t chips a slimming sin?
I’d never cook them at home. But if someone else orders them in a restaurant, I might nick a couple off their plate.

What’s on the menu tonight?
Thai chicken, a recipe from one of my cookbooks. I make low-fat meals, rarely puddings, and I never use any oil or fat, just non-stick pans. You don’t need it.

Isn’t olive oil good for us?
It doesn’t bring anything into your life. If you’re trying to keep down your weight, it’s a disaster. All fats — olive oil, lard or goose fat — go straight on to your thighs for storage.

Would you consider plastic surgery?
No. But ask me again when I’m 80. I have a facial exercising machine that tones up my facial muscles.

If you could change one thing about yourself?
I probably take on too much, but then I like that about myself. The rest of me, I’m quite happy with.

Are you a control freak?
If I wasn’t of that nature, I don’t think I’d head up a company. But I’m less controlling than I used to be. I’ve got a good team at my office that I trust and I’ve mellowed as I’ve got older.

Has your conversion to Christianity helped you to be disciplined?
After inviting God into my life 20 years ago, he has transformed it. The first thing I do in the morning is to pray and read the Bible. It’s good to be self-disciplined; we should take responsibility for ourselves.

Is slimness next to godliness?
I wouldn’t want to connect the two.

Top tip for healthy eating at work?
Stay away from the vending machine. Eat a proper breakfast, and if you get peckish mid-morning have a kiwi fruit or a small apple.

If you hadn’t been a slimming guru?
I would have started a pet rescue home or kept a farm. I love animals. Occasionally I want to tell people that they should put their dog on a diet.

Rosemary Conley’s new fitness DVD, Gi Jeans Weight Loss Workout (£17.99) is on sale now. Her new book, Ultimate Gi Jeans Diet (Arrow, £6.99), is published on January 4