An examination of 350 food products with the words "nature" or "natural" on the label has found half do not form part of a healthy diet.

The survey was undertaken by the Living Lighter campaign, an anti-obesity initiative run by the Heart Foundation and Cancer Council of Western Australia.

Terry Slevin, executive member of the Living Lighter, told 720 ABC Perth half of the products with the words "nature" or "natural" on the label were essentially junk food.

"The kind of claims that they make that a product is 'natural' has been demonstrated by this exercise to be pretty meaningless," he said.

"Most people would have no idea that there are no controls with regard to the use of that title.

"It has become a meaningless marketing term.

"As a result, it not only doesn't help the consumer to make healthy choices — it confuses people and gives them a false sense of security that they are buying things that are good for their family."

Nutrition panels 'hard to interpret'

The study reached its conclusions by looking at the nutrition panels which manufacturers are required to include on packaging, and found high levels of sugar, fats and salt in many of the so-called natural products.

Mr Slevin said the panels were very hard for the public to interpret.

"Not everybody has a dietetics degree," he said.

"It's ridiculous to expect people to have that level of technical expertise."

Changing labels 'unlikely'

Instead many people rely on the labelling on the front of a packet, and Mr Slevin said that was what Live Lighter would like to see changed.

But he said he was not anticipating change any time soon.

"The fight about adequate food labelling has been running in this country for more than 20 years," he said.

"It has been very vehemently fought by the food manufacturers.

"They want to be able to make these kinds of claims because they know it makes a difference to their sales."

In the meantime, Mr Slevin's advice to the public was to ignore claims on packaging and to buy only food that they know is truly natural.

"If people need to make a distinction as to whether something is or isn't natural ... the likelihood is, it's probably not," he said.