But in the world of fad-diets, marketing and celebrity trends, finding the truth about losing weight can be difficult.

In response to this problem, researchers at the University of Newcastle and Hunter Medical Research Institute developed a free course called The Science of Weight Loss: Dispelling Diet Myths.

The so-called "massive open online course" helps people make healthy eating decisions.

It teaches people about evidence-based approaches to healthy weight loss.

More than 55,000 people from 180 countries have enrolled in the six-week course over the past few years.

Professor Clare Collins said the researchers were now seeking about 30 Novocastrians to "help us make this course better".

"We know people find it really valuable, now we'd like to make the course better," Professor Collins said.

Participants will help the researchers evaluate whether the course changes people's diet-related behaviour. They'll need to enrol in the course and fill out some surveys.

"We want them to give us their honest opinion of the course," she said.

"We want to see if it affects their healthy eating decisions or not. As part of that, they'll do our Australian Eating Survey."

In return, the researchers will provide the 30 participants with a personalised report of their diet patterns.

Professor Collins said the course was created to detail "everything that is in a dietitian's head about weight loss".

"This is everything I wish people knew when they see a dietitian and say, 'What's the best diet for me for weight loss?'

"We're trying to arm them with the tools to make a judgement call about whether some random diet they found on the internet is legitimate or not."

The course outlines the basics of weight loss.

"We explain how to measure height and weight, how to calculate a BMI [body mass index] and what that means, so people really feel like they do have the tools," she said.

The course was proving popular probably because it's practical and useful.

"Anecdotally, people are interested in legitimate information about diets and dieting and what is and isn't a fad diet, but they don't know where to get that information," she said.

She said the course was not originally aimed at helping people to lose weight.

"It's a course to help people understand why they might go on a diet and what that does. What we've found interesting is people are applying it to themselves."

When Professor Collins has given talks at seminars - and even while walking across the university campus - people have approached her to share their stories about the course.

They tell her how the course is changing lives, helping them and their loved ones to lose weight.

If you're 18 and over, have internet access and would like to participate in the study, email UONnutrition@newcastle.edu.au.