Overfed but undernourished: not will power, but purchasing power, may determine who eats healthy foods.

• Author: Winterfeld, Amy

In the land of plenty, Americans in growing numbers are obese. The reasons seem obvious--consuming too many calories, exercising too little to burn them away. Not necessarily so.

In low-income communities all across the country, the story is more complicated. The laws of thermodynamics haven't changed, but they're more difficult to apply when healthy foods are out of economic reach.

In lower socioeconomic areas, says Texas Commissioner of Agriculture Susan Combs, "There's a dearth of fruits and vegetables reasonably priced. Yet there's cheap fast food. It's certainly understandable why people opt for a burger for their 8-year-old kid."

Healthy choices are often unaffordable even when local markets stock fresh fruits, vegetables and other low fat, nutrient-dense foods. And it takes more time to prepare healthy, fresh foods, which may be difficult for many working poor families. These families also may need to learn what's healthy and how to prepare it.

Story after story reports the difficulties of locating, affording and preparing nutritious meals for those living at lower income levels.

In Boston, Robin Smith, a hospital worker, has only $30 to $40 a week to spend on groceries for herself and two daughters. That means she can afford the leaner cuts of meat only when they are on sale and fresh vegetables "once in a blue moon."

In Starr County, Texas, where 59 percent of children live below the poverty level, 24 percent of children are overweight or obese by age four, 28 percent by kindergarten, and by elementary school, 50 percent of boys and 35 percent of girls are overweight or obese. Almost half of the adults in the Star County, the poorest in Texas, have type 2 diabetes, and nearly every child is at risk for the disease because a close relative (parent, sibling, aunt or uncle) is already afflicted.

California farm worker Iris Caballero is overweight and diabetic, but cannot always afford the produce in the state's central valley, which also has some of the nation's highest poverty rates. During harvest season, when she works picking grapes and oranges, Caballero can find and purchase fruit in the local mini-market. In the winter, when work and fruits and vegetables are hard to find, Caballero depends on the cheapest food available to feed her family--potatoes, bread and tortillas.

Untreated diabetes caused the blindness of a 15-year-old student in Caballero's community, but served as the impetus for a free nutrition class for farm...