THE old diet trick of using a smaller plate to bluff your brain into eating less doesn't work, and can even make you eat more, scientists have found.

The new report published in the journal Appetite reveals when people are hungry, especially when dieting, they are unlikely to be fooled by the plate size and are inclined to realise they are eating less and overeat later.

Hunger stimulates stronger analytic processing than the plate illusion.

Portion size is one of the biggest contributors to the state's obesity crisis, but Nutrition Australia's Aloysa Hourigan says there is more to eating less than the size of the plate. Listening to hunger cues and eating more slowly play a part too.

"Portion sizes have grown over the generations," Ms Houirigan said.

"We use to have plates the size of bread and butter plates for main meals.

"Today's society is all about upsizing and offering all-you-can-eat deals."

The research is from the public health research university Ben-Gurion University of the Negev.

Larissa Hlinovsky watches her food intake. Picture: Annette Dew
Larissa Hlinovsky watches her food intake. Picture: Annette Dew

A 2018 report by the Australian Institute of Health and Welfare found upsizing of portions had been a contributor to the number of severely obese Australian adults almost doubling since 1995.

"It is important to train yourself to eat less," Ms Hourigan said.

"That means taking your time, putting down your knife and fork between bites and being mindful and not rushing.

"Also, if you are still hungry after eating, get up and distract yourself with something else. The brain takes time to register being satisfied."

Nutrition Australia recommends filling one-quarter of the plate with protein, one-quarter with starchy foods such as sweet potato, and the remaining half with vegetables.

Larissa Hlinovsky, 29, from Carindale, says she has to watch her food intake.

"I think that eating more smaller healthy meals on small plates throughout the day helps keep you more sustained than sitting down to one really big meal," she said.