In recent months, RAND researchers have teamed up with a dozen Los Angeles lunch trucks to test healthier menu items—chicken breasts and grilled fish alongside the usual tacos and hamburgers. The results have been modest but promising. The healthy meals were never best-sellers, but they did well enough that a majority of the truck owners plan to keep them on the menu.
    That's important, because the trucks tend to serve working-class Latino communities, where obesity rates are high and healthy food can be scarce, leading researcher Deborah Cohen said. "It's important that the providers are offering these meals," she said. "I think what we showed is that it's completely feasible."
    Cohen has spent years arguing that restaurants, grocery stores and other food outlets should take more responsibility for the nation's obesity epidemic, and more action to stop it. More than one-third of U. S. adults are obese, according to federal statistics, adding billions of dollars to the nation's health care costs each year.
    A lunch truck may seem like an unlikely testing ground for healthy menu items, the four-wheel equivalent of a fast-food joint. But most are morn-and-pop operations where cooks make food by hand, using fresh ingredients and often for underserved communities. Cohen called them a "good lab."
    These aren't the trendy food trucks that have started to sell fusion tacos and reimagined grilled cheese to hip, young urbanites. These have been part of blue-collar Los Angeles for generations, where they're known as loncheras, after the Spanglish word lonche, for lunch.
    Working with a $ 275,000 grant from the National Institutes of Health, RAND researchers enlisted nearly 20 loncheras for a six-month trial they named "La Comida Perfecta," or "The Perfect Meal" About a third of the truck owners later dropped out, leaving 12 who worked with a nutritionist, created their own healthy meals, and then put them on the menu.
    The six-month pilot program didn't yield big sales numbers at most trucks, but it did yield some valuable insight into the challenges, big and small, of changing food habits, the researchers said. Truck operators had trouble swapping out their corn tortillas for whole wheat, for example, and their Latino customers especially didn't care for the brown rice that replaced their traditional Mexican rice. Nearly half of the truck customers were regulars, surveys found, and most knew what they wanted without even looking at the menu. In poorer neighborhoods and blue-collar work sites, that was usually a couple of $1 tacos, not a $7 plate with fruit and salad.  Cohen may agree that ______.