Australians spend thousands of dollars on diets with the sole purpose of losing weight, but now there is a diet aimed at maintaining youth and Donna Aston is living proof of its success.

Ms Aston is a diet guru and body-sculpting champion who works with celebrities such as Sigrid Thornton.

"People are not aware of the impact food, nutrition and exercise can have on health and wellbeing and appearance," she said.

"We can't stop the clock, but we can certainly slow down the process of ageing."

Her latest book is aimed at age-proofing your body from the inside.

"We need to eat more fresh foods, fruits and vegetables, protein foods, nuts, oils, natural foods," she said.

The focus here is on food rather than on exercise and it starts with a visit to the local greengrocer.

Ms Aston says there are a few key vegetables that are packed with anti-ageing nutrients.

"Garlic is absolutely wonderful - great in cooking and really good for the immune system," she said.

"Tomatoes are wonderful. They are full of an antioxidant known as lycopene - great for preventing prostate cancer in men."

Ms Aston says the dreaded sprouts help prevent cancer and are very healthy but her ultimate vegetable is spinach, which is high in folic acid and antioxidants.

Contrary to the old food pyramid and expert opinions from other nutritionists, she recommends seven to ten serves of fruit and vegetables a day.

But even ten serves is not enough for Ms Aston - she believes we should also take vitamin supplements, because we do not eat enough fruit and vegetables every day.

"The bottom line is most of us don't, so it is best to try and cover ourselves," she said.

And if you want a complete cocktail, Ms Aston recommends adding a natural fish oil, folic acid and grapeseed extract to your multivitamin, all washed down with two litres of water a day.

So let's try this eat-yourself-young thing in the real world.

Angela Schastenaar is in her 30s and works in a demanding PR job.

She feels a bit tired and, like most people, she's conscious of her weight.

On a typical day she eats porridge with tinned or fresh fruit and yoghurt for breakfast, some tim-tams during the morning, a takeaway lasagne for lunch and dinner at a restaurant or noodles, with some dried fruit or liquorice for a treat.

Now for the anti-ageing makeover.

Ms Aston suggests Ms Schastenaar tries eating fresh fruit instead of dried fruit, and rolled oats instead of porridge.

She also suggests adding whey protein.

She says Ms Schastenaar should eat an orange rather than have orange juice as that will give her extra fibre.

She also recommends filling up on nuts.

For lunch she suggests a salad, which can be made more substantial with cheese, avocado and flaxseed oil.

Dinner can be a chicken vegetable stir-fry and for dessert, some fresh berries with yoghurt.

It looks colourful and bountiful but isn't it a big effort remaining well preserved, energetic and youthful?

"I can't think of anything harder than living in a body that is tired," Ms Aston said.

"For me, the easiest thing is following the principals and feeling fantastic all the time."