If you’ve ever tried to complete a work day or study for a test on an empty stomach, you probably understand the importance of a healthy stable diet for success. For students, that fuel usually comes in the form of daily school lunches, yet, for millions of American children, paying for school lunch is a luxury they simply cannot afford.

A report released by UNICEF found one in five American children falls below the poverty line. Of the 35 countries the report analyzed, the United States ranked a shocking 34th when it came to child poverty. That all adds up to nearly three million American children officially recognized as food insecure by the US Department of Agriculture. When these children return home from school, the prospect of a hot meal waiting for them on the dinner table is far from certain. The lunch provided at school could be the only meal they eat all day.

A school lunch might not initially seem like an expensive line item, but those lunches can add up. In some cases, students and their families are taking on school lunch debt, sometimes with dire consequences. Earlier this month a school district in Pennsylvania threatened to have children removed from their families and sent to foster care if their parents did not pay off their lunch debt.

Luckily, many of these students can benefit from free and reduced-cost lunches through a federal subsidy called the National School Lunch Program. First formed in 1946 under the Truman Administration, the program has since expanded and helped fill the bellies of 30.4 million kids in 2016. Nearly 100,000 of an estimated 130,000 US schools voluntarily participate in the program. Public schools and non-profit private schools all around the country receive cash subsidies from the federal government and use those subsidies to provide lunches to students free of charge.