A detox regimen of lemon juice and choosing foods based on your blood type have been voted among the worst fad diets by Australian dietitians.

More than 50 nutrition experts took part in the Dietitians of Australia online survey, which asked them to list their three worst diets.

The survey results were released today in a bid to steer young women away from fad diets in the new year.

Eighty per cent of dietitians thought the lemon juice detox diet, which sees participants repeatedly drink lemon juice with cayenne pepper, was the worst.

This was followed by the blood-type diet, which focuses food intake around your blood type, and the acid and alkaline diet, which focuses on fruit, vegetables and legumes.

"Women often think they are failures when they can't sustain such strict and unrealistic diets," DAA spokesman Trent Watson said in a statement.

"The truth is, it is the diets that are failing young women."

Dr Watson said people should ditch the fad diets and focus instead on regular exercise and healthy eating.

"Small sustainable changes over the long-term are much more effective than yo-yo dieting," he said.

He encouraged people to eat breakfast every day, limit take-away meals to once a week, choose water as a drink and exercise most days.

ABC/AAP