A survey of 500 primary school aged children found 43 per cent skipped breakfast with those in NSW and the ACT more likely to do so because they were time poor.

The research also found 91 per cent of children felt hungry when in class, with those who skipped breakfast more likely to become grumpy and disruptive.

Fiona Loaney said her children always ate breakfast although they often became cranky and short tempered when their blood sugar levels fell in the afternoon.

"It's concerning so many kids are not having food before they go to school, whether it be cereal, toast, eggs or anything else," she said.

Dietitians Association of Australia spokeswoman Tania Ferraretto said eating breakfast was a "no brainer" for school students.

"It is crucial for children – giving them the chance to take in key nutrients like B vitamins, folate, iron and fibre," she said.

"We know through research that breakfast plays a key role in improving mental and physical performance."

The research found a majority of children knew they needed to consume fruit and vegetables every day but were not aware of other core food groups.

"We're increasingly seeing breakfast become a meal that's eaten on-the-run, or not at all, as families battle to manage hectic mornings," Ms Ferraretto said.

"It's time to reprioritise and find solutions that ensure five minutes is set aside each morning for breakfast."

Amanda Salis, a senior research fellow at the Boden Institute of Obesity, Nutrition, Exercise at Eating Disorders at the University of Sydney, said "hanger" was a complex issue with many causes.

"There are several pathways that can make you prone to anger when you're hungry," she said.

"Hanger is undoubtedly a survival mechanism that has served humans and other animals well. Think about it like this: if hungry organisms stood back and graciously let others eat before them, their species could die out."