Kids are fussy and they constantly change their eating habits, Melbourne chef James Cornwall told ACM.

"Being a chef is not as much of an advantage as you would expect".

"I find that keeping kids happy with their lunch box is tougher than keeping guests happy in the restaurant," the ex-head chef of London institution, J Sheekey, said.

Mr Cornwall worked in Melbourne restaurants, Iki Jime and Cumulus Inc. before opening Tenable Dining, overseeing food service at Fitzroy's Bonny and Ms Botanica in Yarraville.

The moment you think "that you've cracked it", children change their mind and lose enthusiasm for what you've been making, Mr Cornwall said.

"You have to start all over again," he said.

To keep kids interested in their school lunches, Mr Cornwall recommends swapping between breads, wraps and buns and slipping in some grated carrot.

"Carrot tastes great with most fillings and goes unnoticed, so it's a great way to sneak veggies in," he said.

Carbohydrates are a lunchbox staple for a reason, University of the Sunshine Coast clinical placement coordinator and dietitian Angela Cleary told ACM.

"Multigrain or whole grain bread is great for energy."

"The less processed, the better," she said.

There are no superfoods or magic bullets, but try to get a range of fruits and vegetables into the school lunch, Ms Cleary said.

"Having different colours means you're going to get a variety of vitamins and minerals," she said.

A reliable favourite among kids is carrot or celery sticks with hummus, Ms Cleary said.

Mr Cornwall recommends substituting hummus for butter on sandwiches for a flavorful, healthy alternative.

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Make sure the family eats breakfast before heading to school, Ms Cleary said.

"So you're not starting the day hungry," she said.

For Mr Cornwall, the school lunch starts in the mornings with a fruit smoothie as the family is rushing out the door.

"We add a mixture of frozen fruits, a small amount of spinach, [that] they don't even notice, and kids chocolate protein powder," he said.

"We try to pack as much nutrition and energy into the start of their day as we can," he said.

Another tip is to consider the container the lunch is served in and whether the quality of food will remain across the day, Ms Cleary said.

"No one's going to eat the squashed banana," she said.

Having an insulated lunchbox means parents can safely send high protein snacks like yoghurt to school, the dietician said.

"It's great if you can keep it cold," she said.

"And make sure they have a nice big water bottle with some ice cubes," she said.

A wide top thermos is Mr Cornwall's lunch box favourite. He likes to send his children off with last night's leftovers or some warm soup on a cold day.

"We sneak lots of finely cut vegetables into our kid's spaghetti Bolognese, but fried rice with chicken and vegetables is their favourite," he said.

Popcorn, made at the beginning of the week, salted lightly and bagged individually is a great lunchbox treat, the chef said.

"And home-made muesli bars are great because you can control the amount of dried fruits, chocolate and sugar going into each one," he said.

"But don't be too hard on yourself, there are no good foods and bad foods," Ms Cleary said.