According to research by the Children's Society charity, more than half of the 2.2 million children living in poverty in England miss out on a free school meal every day.
Around 700,000 of these are not entitled to one, and a further 500,000 do not take them up because a fear of being stigmatised, the charity said.
Matthew Reed, chief executive of The Children's Society, said:
This report sets out shocking evidence of just how much hardship teachers up and down the country are witnessing in classrooms day in, day out.
Something is going badly wrong when teachers themselves are having to feed children.
Every child in poverty should be given a free school meal. Free school meals are key to moving children out of poverty and vital to helping them flourish.
More top news
Man's best friend really does understand some of what we are saying, scientists are suggesting.
Selena Gomez said she was taking time out to deal with panic attacks and depression thought to be a side effect of her lupus disease.
Temperatures will be highest in the southeast, reaching a high of 24 Celsius (75F) here.