Latest research has revealed the best way to lose weight is to shed flab as fast as possible.

But high-profile Auckland personal trainer and sports nutritionist Lee-Anne Wann has dismissed the Melbourne University findings.

She is adamant losing weight slowly over a long period of time is still the best way to go.

The Melbourne study was presented to an international obesity conference in Stockholm last week.

It compared a rapid diet - with subjects weighing about 100kg losing 1.5kg a week for 12 weeks - to a 36-week diet in which participants lost 0.5kg a week.

Wann disagrees the fast way is best. "It is yet another way for people who struggle with weight loss to be made to feel bad or feel they are not good enough if they fail," she says.

Wann believes working weight loss into a person's lifestyle and helping them make small changes on an ongoing basis achieves better results.

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

Wann says results that will last and that allow a person to enjoy the journey are important. She says for heavier people, small changes will make a big difference.

"And those who just want to shift the last few kilos would benefit from small steps as any extreme at that point will cause the body to go into survival mode," she says.

Melbourne researcher and dietician Katrina Purcell says four people on the gradual diet gave up before the end of the experiment, compared with only one in the rapid diet group.

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

One explanation could be psychological, as those achieving higher weight loss remained more motivated.

Nutrition and weight loss expert Damian Kristof says the results of the study are "terrific" and supported rapid dieting - but not fad dieting.

Fad diets - what are they
Atkins Diet: Severely restricts carbohydrates, allows a lot of protein and fat, and encourages meat, poultry, fish, eggs, cheese and low-carb vegetables.

Lemon Detox Diet: No solid food for up to 10 days and live on a juice of lemon juice, maple syrup and cayenne pepper. Detoxers must also drink a litre of sea salt water every morning and a detox tea each night.

Cabbage Soup Diet: Involves eating as much of the soup as possible, incorporating a different solid food each day, including milk with bananas, steak and fruit.

Grapefruit Diet: Based on the theory that the enzymes will make you lose weight, dieters eat half a grapefruit before meals.

Gabriel Method: A "non diet" approach to weight loss that uses the power of the mind through visualisation and positive thinking to turn off the body's "fat switch".