Despite tall claims that diet shakes could aid in weight loss, nutritionists are skeptical about their effectiveness.
At least 15 brands of diet shakes - some promising "a new you" in a matter of weeks - are on the market in Australia.
The Dietitians Association of Australia said 95 percent of all dieters would regain their lost weight in one to five years.
Weight Watchers' nutritionist Emma Stirling said the key concern for many health professionals is that meal replacement shakes are a temporary fix.
"Contrary to popular belief, there is no miracle weight-loss cure or proven fat-blasting ingredients lurking within a chocolate diet shake," the Sydney Morning Herald quoted her as saying.
"They are simply a combination of vitamins, minerals and other additives in a flavored milk or water-based drink.
"Diet shakes are designed to be partial meal replacements, where one or two meals a day are replaced with the shake and the remaining meals made up of regular food," she explained.
She said that eating a couple of small pieces of fruit instead of a couple of meals a day would create the same loss of calories.
Dr Ken Harvey, senior research fellow at La Trobe University's School of Public Health, said his main concern with the diet shake industry was the unsubstantiated miracle weight-loss claims being made by several companies.
He filed a complaint to the Therapeutic Goods Administration's complaints resolution panel about Pharmacare Laboratories' Xantrax shakes after the company claimed that "'a new slimmer you is less than 30 days away - with the doctor-recommended diet shakes".