They reckon Paleo should be kept in a cave, the Mediterranean diet is as blessed as the sun, while flexitarian is smart because you can still smash a steak here and there.

Now a new study debunks the idea of best and worst or right and wrong. Instead, the study - a review of the clinical diet trials of more than 7200 adults - says any diet will do the trick. So long as you stick to it.

Weight loss differences between these popular diets are minimal, said the researchers, who loooked at Atkins, Weight Watchers, Zone, Jenny Craig, LEARN, Nutrisystem, Ornish, Volumetrics, Rosemary Conley, Slimming World and South Beach diets.

"Given the popularity of these diets around the world, there has been a real lack of research to examine their relative benefits," said co-author associate professor Geoff Ball of the University of Alberta. "But overall, the differences between the different diets regarding their impact on weight loss were relatively small."

To come to this conclusion the researchers assessed weight loss among participants at six and 12 month intervals.

They found those on a low-carb diet had maintained a weight loss of around 8.75 kilograms at the six month mark and 7.25 kilograms at 12 months. Those on a low-fat diet had lost around 7.9 kilograms at six months and 7.2 kilograms at 12 months.

"Weight loss differences between individual named diets were small," concluded the authors, who were looking at weight loss, not health outcomes. "This supports the practice of recommending any diet that a patient will adhere to in order to lose weight."

Amanda Salis of the Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders says the "strength of the findings is very robust".

Although the idea that any diet works if you stick to it is correct, she says there is one important caveat. There is the widely quoted statistic that 95 per cent of dieters regain the weight they lost within several months or years.

While this figure is not accurate, many do regain the weight, with some putting on even more than when they began.

A maintainable approach therefore is more important than the diet. Or is it?

"Some diets are easier to stick to than others," she explains.

The Diogenes project, funded by the European Commission, put participants on one of five different maintenance plans.

They found that those most able to maintain weight loss was the group on a low GI, moderately high (not Paleo-high) protein diet.

"This diet was significantly better for keeping weight off long term," Salis says, explaining that the combination of protein and low GI meant people tended to feel more satiated on less.

But, there is also the idea that all these studies are based on averages and individuals fare differently on various diets.

"The issue is about adherence and it's how closely and how long can you keep sticking to the plan over time that matters," Professor Susan Jebb, from the University of Oxford and a government advisor on obesity, told the BBC.

"That probably means finding the right diet for you, rather than one being so particularly better than the others."

Salis agrees.

"There is no one single perfect diet for everyone. Some people have been shown to do better on very low carb diets and others have been shown to do better on moderate carb diets.

"There is truth in eating for your type. The trouble is we don't yet know how to predict which type is best for you."

That, she says, is an issue being explored in current research. In the meantime, there is no need to follow the fads; just a little healthful attention to our diets any which way will do the trick.

Amanda Salis is currently recruiting participants for clinical trials on the long-term effectiveness of different weight loss diets. For more information please email her team on tempo.diet@sydney.edu.au