Researchers at Children's Hospital of Philadelphia said even short-term poverty can have a long-term impact on a child's health.
Their study found that in 2008, 21 percent of children live in households where food is "insecure". This is the highest rate since 1995.
The research also found that 43 percent of families with children said they don't have stable housing.
Experts encourage low-income families to safeguard their kids by enrolling them in "safety net" programs offered by the government, such as Medicaid.