Lawmakers in a House committee say they're concerned that a voluntary program aimed at curbing the amount of junk food available to students isn't working.

That's why they gave initial approval to a bill Thursday that would require schools to stock half of all their vending machines with nutritious snacks.

Erin Bertoli of the American Heart Association says 16 percent of children in public schools are obese and could be at risk of severe health consequences.

But school officials say the mandate could lose revenue for schools, which use the money for athletic and other school programs.

Representative Al White, a Republican from Winter Park, voted against the bill, saying the state has no business telling local school districts what to do.