Congress should boost spending on U.S. child nutrition programs by nearly 10 percent to ensure year-round meals for all children and to help children learn healthful eating habits, anti-hunger groups say.

In a letter Wednesday to congressional Budget and Agriculture committees, the groups asked for an additional $1 billion a year "for important improvements in child nutrition programs," which must be reauthorized next year.

Congress will review the programs at the same time that reports indicate 15 percent of children were overweight, up 4 to 5 percentage points in a decade.

Activists said they wanted to ensure children from poor working families had access to school lunches, to help children learn about healthful diets, and to broaden eligibility for food at preschool, after-school and summer programs.

"The stronger these programs are, the better off children, schools and communities are," said Jim Weil, president of Food Research Action Center, one of 45 school, religious and anti-hunger groups that signed the letter.

While aimed at feeding children, the programs result in lower infant mortality and higher learning rates, Weil said. The letter said "funding for these programs has not kept pace" with rising expectations for them.

School lunches, for example, are required to comply with the Dietary Guidelines for Americans -- which try to limit fat in the diet and encourage more consumption of fruits and vegetables -- although federal reimbursement rates have fallen since the 1970s.

"The child nutrition programs present opportunities for positive role modeling of healthy and nutritious meals, from birth through the teen years," the letter said.

Meals are free for poor children, offered at a reduced price for low-income children and available at full price for others. The cutoff line for free meals is 130 percent of the poverty rate, or an income of about $23,500 a year for a family of four. Full-price meals begin at 185 percent of the poverty rate, or about $33,500 a year for a family of four.

About 27.5 million children are fed each school day through the federally supported school lunch program, 59 percent of them free or at reduced price.

About 7.8 million children eat daily through the school breakfast program, and 2.7 million children and adults participate in a day-care food program. Nearly 131 million meals are served during the summer food program.

WIC provides supplemental food to about 7.3 million pregnant women, new mothers and their offspring each month.