Rachael Devcich fell in love with extreme fitness sport CrossFit three years ago. The only problem was that no matter how much she ate, the intense workouts left her ravenous.
So, like many CrossFitters, she turned to the paleo diet. The 42-year-old art director and mother of two did away with grains, soy and pulses. Out, too, went processed food. In came more meat, seafood, poultry, dairy and whole fruits and vegetables.
"At first I thought, 'Oh my God, that just sounds ridiculously limiting,"' she said. "But I tried it for a week and I'd never felt so good."
The diet is one version of the popular clean eating approach to food, whose devotees include Kim Kardashian and Nicole Kidman.
Mrs Devcich now runs a website - cavegirl.co.nz - dedicated to the principles of clean eating. It attracts about 1000 visitors a month. "It is just eating real food - nothing that is chemically or heavily processed."
Many of the principles of clean eating are sound, says nutritionist and healthy food guide author Claire Turnbull. However, when taken to extremes or interpreted incorrectly, the diet can be harmful.
"There is no exact definition of what clean eating is," Ms Turnbull said. "It means different things to different people. A lot of it is tied up with the fitness industry, with personal trainers putting out their own guidelines ...
"There are some very extremist points of view on this. You may be eliminating things you don't need to be eliminating, and it does create this obsession with eating. A lot of people I meet have created this very dysfunctional relationship with food by trying to follow these rules."
Health mentor Jason Shon Bennett's company offers programmes based on the health benefits of plant-based whole foods.
His programmes incorporate many of the principles of clean eating, but he warns against expecting a quick fix when it comes to improving health through what you put in your mouth.
"We need sleep, we need exercise, we need low stress and we need routine, good food, fibre, green vegetables, antioxidants - we need all these things to be healthy."
It might be popular with the well-off, but clean eating wasn't likely to reduce the country's alarming obesity statistics, Ms Turnbull said.
"It is the healthy people who are trying to get healthier that these kind of messages go around with. Do they make a jot on national obesity rates - very, very unlikely.
"You go to Ponsonby and there are these beautiful organic stores. But just go 20 minutes down the motorway and every school is surrounded by takeaway shops."
*Eliminate processed foods.
*Eat whole foods, mainly fruits and vegetables.
*Limit fat, salt and sugar.
*Eat five to six small meals a day