Wellington, April 30 NZPA - A group of Otago University researchers has told MPs involved in a weight loss contest that they're sending the wrong message and putting their own health at risk.

Parliament's "biggest loser" competition started this week when five Maori MPs each put in $20 and challenged each other to lose weight over the next two months. It is catching on.

They thought it was a good idea to promote weight loss programmes but two professors and three doctors say it isn't.

"We are deeply concerned about the risk of publicising a quick-fix, celebrity-styled approach to an ingrained health problem that is not only highly likely to fail in the medium-long term and potentially put your own person health at risk in the in the process, but the 'biggest loser' stunt is sending exactly the wrong message to the public," they said in an open letter to Hone Harawira, Tau Henare, Mita Ririnui, Parekura Horomia, Kelvin Davis, Shane Jones, Paul Quinn and Simon Bridges.

"It is easy to lose weight; it is keeping it off permanently that is the real issue."

Professors Jim Mann and Doug Sellman and doctors Ria Schroder, Jane Elmslie and Frances Carter said the "biggest loser" format was about a short-term project involving large weight loss quickly rather than a more patient, slow, permanent lifestyle change.

"We urge you to consider a change in the format of your public therapeutic endeavour," they told the MPs.