When Dan Giusti was head chef at Denmark's Michelin-starred Noma, regularly voted one of the world's best restaurants, he served prepared dishes with locally sourced ingredients and lavish prices.

Now he feeds thousands of underprivileged children at public schools in the United States, offering wholesome meals on a budget of $1 apiece through his consultancy firm Brigaid, which last week began training cafeteria staff at nine more schools.

"The students are not eating much, if anything, outside of school ... so these meals are absolutely crucial," he told the Thomson Reuters Foundation by phone from Connecticut, where he is based.

Giusti founded Brigaid three years ago and hopes to take its services nationwide.

"The kids that go to these public schools are attending school from a very young age all the way to 18 so you really have an opportunity to get to them in terms of feeding them and getting them to think differently about food."

In 2018, one in nine American households or 37.2 million people were hungry, with the figure going up to one in seven in households with children, according to the US Department of Agriculture.

A Brigaid chef currently serves three meals a day to more than 3,600 schoolchildren in eight schools in New York City and Connecticut under the National School Lunch Program, which provides free or reduced meals.

Globally, one in four people, or two billion, lack access to healthy food, the United Nations Food and Agriculture Organization has said.

The schools receive slightly more than $3 per lunch in subsidies from the federal government and have about $1 per meal to spend on food after covering the cost of labor, equipment and other items such as milk to drink.

Giusti said he intended to speak out on issues such as a need for federal policy changes, much the way British chef Jamie Oliver spoke out to help improve school nutrition in the UK more than a decade ago.

He said he learned that changing people's minds can take time and patience after taking peanut butter and jelly sandwiches off a school menu.

The move prompted one school boy to cry, and he said he realized the reason he stopped serving the sandwiches was his own ego.

"These are kids who are dealing with really challenging situations outside and inside of school," Giusti said.