A weight-loss device described as "medical bulimia" that drains undigested food from the stomach at the press of a button is among an explosion of new treatments for obesity available in Australia.

As concern continues to grow about obesity, some doctors are alarmed that some treatments in the lucrative market aren't being adequately researched or followed up.

The Australian Therapeutic Goods Administration-approved AspireAssist system connects a tube inserted into the stomach to an outside port on the skin of the belly, which is drained into an external device.

Its American manufacturer promises about 30 per cent of food is removed before calories are absorbed into the body when used 20 minutes after a meal.