Hawai'i public schools are sending a healthier message to students this year by curbing the sales of soda in school vending machines.

Secondary schools have some discretion, but on elementary school campuses, at least, students won't have access to machines that sell more than milk, flavored milk, water or fruit juice.

It's a reasonable first step. Children can't develop good eating habits while surrounded by food and beverages that offer little more than sugar's empty calories. Recent studies deliver the distressing news that close to half the nation's elementary schools, and a much higher proportion of middle and high schools, sell less-than-perfectly-healthful snacks to students.

Eliminating vending machines assists the larger campaign to improve the diets of our students, many of whom fight a continual battle with childhood obesity. In schools where there's also a strong health curriculum beating the drum for good nutrition and fitness, the message becomes a little clearer.

But it's unrealistic to expect schools to right the wrongs of America's eating habits, which are born in homes and reinforced at every turn. Most students who avoid junk food on campus can walk a few hundred yards and purchase it in the neighborhood.

Behaviors arising from family patterns and external influences won't improve without altering the way we think about food — a fix that's not easily dispensed through a vending machine.