Community gardens have sprung up all over the country — on abandoned or vacant city lots, on church properties, in school yards, and even in the ‘burbs. The fresh, healthy produce grown in them is obviously their major contribution to public health, but a new study has found that community gardens have other unexpected health benefits. They offer opportunities for physical activity, social interaction and they may help you lose weight, too.

In the United States community gardens date back to the 1890s. They began as a way to aid unemployed workers in large cities and to teach good work habits to young people. During World War I, the government promoted them as a way to supplement the domestic food supply. In the Great Depression many of the poor and unemployed grew their own food. World War II saw the rise of Victory Gardens. But few gardening programs remained after the war until the 1970s, when today’s community gardening movement began.

Women gardeners' BMI was 1.84 lower than neighboring women who had never touched a spade. This difference in BMI translates into an 11-pound difference in weight for a woman who is 5 feet 5 inches tall. For men, the difference was even greater.

It is no surprise that people who work in community gardens and eat the fruits and vegetables of their labors are healthier, but as Cathleen Zick, lead author of the study, explained, "It has been shown previously that community gardens can provide a variety of social and nutritional benefits to neighborhoods. But until now, we did not have data to show a measurable health benefit for those who use the gardens."

And what is this unheralded health benefit? A lower body mass index — and far lower odds of being overweight or obese. Gardening is good exercise, and you eat pretty well, too.

Compared to their neighbors who didn’t participate in the garden, community gardeners had lower BMIs. Women gardeners' BMI was 1.84 lower than neighboring women who had never touched a spade. This difference in BMI translates into an 11-pound difference in weight for a woman who is 5 feet 5 inches tall. For men, the difference was even greater.

The same was true when researchers looked at the siblings of gardeners. This shows that gardeners' healthier weight was the product of the opportunities for exercise — for digging and raking and weeding — as well as eating, that community gardens provide. In fact, when the BMIs of gardeners and

Though the study was small and limited to participants in only one community gardening organization, Zick notes, "…as the percentage of Americans living in urban areas continues to grow, this initial study validates the idea that community gardens are a valuable neighborhood asset that can promote healthier living."

Urban planners and public officials — and citizens — take note.

The study is published online in the American Journal of Public Health.