How to win the battle of the bulge is an age-old question with no concrete answer.

But according to new research, there's one unlikely method which can see Australians' weight loss quintuple - and it has nothing to do with exercise.

Functional imagery training - or FIT, a coaching method which teaches how to focus on reaching a goal weight - is being lauded as the secret, following a new study.

More specifically, FIT uses multi-sensory imagery to explore the desired changes by teaching clients how to elicit and practice motivational imagery themselves.

In the study, all 141 participants had a BMI of at least 25 - rendering them overweight.

According to new research, there's one unlikely method which can seen weight loss quintuple - and it has nothing to do with exercise

While 55 tried two sessions of motivational interviewing therapy, the remaining 59 underwent two sessions of functional imagery training.

Comparatively, MI focuses on counsellor support which aims to develop, highlight and verbalise their need or motivation for change, along with their reasons for wanting to.

Both groups received follow-up sessions for three months and then once monthly for another three months.

By engaging in therapy which made them made them visualise the changes they planned on making, participants shed five times the weight of those who didn't.

After six months, those who used the FIT intervention lost an average of 4.11kg, compared with an average weight loss of 0.74kg among those who didn't.

After six months, those who used the FIT intervention lost an average of 4.11kg, compared with an average weight loss of 0.74kg among those who didn't

Interestingly, a further six months after the intervention – the FIT group continued to lose weight, losing an average of 6.44kg compared with 0.67kg in the MI group.

'Most people agree that in order to lose weight, you need to eat less and exercise more, but in many cases, people simply aren't motivated enough to heed this advice – however much they might agree with it,' said Dr Linda Solbrig who led the study.

'It's fantastic that people lost significantly more weight on this intervention, as, unlike most studies, it provided no diet/physical activity advice or education.

'People were completely free in their choices and supported in what they wanted to do, not what a regimen prescribed.'