Updated

A controversial weight-loss study found the best way to shed flab is to do it fast, The (Sydney) Daily Telegraph reported Friday.

Dietitian Katrina Purcell presented a study to an international obesity conference in Stockholm this week which defied conventional wisdom that "slow and steady" was the best way to permanently ditch those muffin tops.

"Surprisingly and against current beliefs this study shows rapid weight loss appears to be superior to gradual weight loss in achieving target weight," she said.

Her results found 78 percent of those on the rapid diet achieved the target loss of 15 percent of their body weight within the period, while only 48 percent of those on the gradual diet met their target.

In fact, four people on the gradual diet gave up before the end of the experiment, compared with only one in the rapid diet group.

Purcell said one explanation could be psychological, with those achieving big weekly results remaining more motivated. The dietitian, however, warned against crash diets, in which weight was lost very quickly by slashing calories. "Don't do it by yourself, do it with a dietitian," she cautioned.

Dietitians Association of Australia spokeswoman Melanie McGrice said the heavier you were, the easier it was to shed weight quickly.

But she warned that "what you lost" was more important, with crash diets likely to strip the body of muscle tone and water than targeting fat cells.

"If you're going to go on a diet where you're losing weight quite quickly, you need to maintain your nutritional requirements," she said.

"Research has shown if the weight is lost slowly you keep it off."

Conventional weight-loss wisdom holds the quicker it comes off, the quicker it returns — with interest — so Purcell plans to follow her subjects over the next three years to see which of the two groups best maintains their target weight.