With her trim figure, long blonde hair and blue eyes, Calgary Avansino looks the epitome of a healthy Californian. But she’s made Britain her home for the past 16 years, where, as part of the burgeoning cleaneating brigade, she’s transforming our daily diets.

New cookbook Keep It Real is packed full of wholesome advice from the mum-of-three (to Ava, Margot and Remy), who arrived here in the winter of 2000, to discover coconut water and quinoa were unheard of, let alone available in local supermarkets.

Now, of course, they’re ubiquitous, but we’re still making bad decisions about what we put in the trolley.

“I think we’ve lost a reality check about what real food is, because we’re so used to going down the grocery store aisles and seeing 50 cereals and 20 salad dressings and actually, none of that is real food,” says the journalist, who, unsurprisingly, looks much younger than her 40 years.

“So, what you’re used to doing - you have to stop that habit. Think about food in terms of where it comes from, what it’s made from, what goes into it, and start caring about what we put in our bodies in a different way.”

Avansino, who started her career in journalism as the assistant to British Vogue’s editor-in-chief Alexandra Shulman and is now a contributing editor, has a simple set of rules for how to “keep it real”, which include: Ditching diets, embracing plants, and eliminating sugar.

“When I talk about a plantbased diet, it doesn’t mean you have to be a vegan or veggie at all; if you want to eat lean, good cuts of meat, that’s fine. You just have to look at what else you’re eating,” she says. “I’m not saying make three-starred Michelin meals, I’m just saying chop some spinach.”

It was really important for Avansino that her book be published post-January, so it wouldn’t be part of the “detox, diet mentality”.

“This is forever. You have to decide if you want to change how you think about cooking and the food you put in your kitchen. It should be a great thing – not a deprivation thing.”

Diets are off the menu completely.

“Diet is such a negative concept. It causes this cycle of, ‘I’m not good enough, I’m a failure and I can’t do this – and now I weigh more than I did before’.

Because that’s what happens – every time.

“I think there’s a huge movement against dieting and that’s what I want to see – because I don’t want anything I write to be thought of as a diet.”

So that means you can indulge in your favourite food, be that pizza or brownies, but she says: “You just can’t have it all the time”.

“Especially with women, there’s this mentality where if I eat something naughty for breakfast then I think, ‘Oh well, this day is shot, I might as well eat crap all day’. But think of every meal as a fresh start.

“Don’t ever beat yourself up about something you ate before – just move on and start with the next meal, day or whatever it is. Don’t make food the enemy.”

Exercise is also really important – a self-confessed yoga bunny, when she started at Vogue, she would arrive freshfaced from a morning workout to find her colleagues nursing coffees and giving her odd looks.

In her book, she says we must make an effort to move our bodies every day.

“I don’t find exercise a burden – it just makes me feel more levelled, calm and less stressed. I have really good ideas when I’m working out.”

The whole family go hiking when they’re back in California - or walk around the parks in London.

She’s bringing up her children to make healthy choices, but she’s careful not to micromanage them so much that they can’t indulge at birthday parties.

“I always try to teach my children moderation – just choose what you want most and enjoy it.”

And that sounds like good advice for us all.