Current economic conditions create a food environment that places the poor at highest risk for unhealthful diets and obesity. Unhealthy food simply costs less than healthy food, and is much easier to find. Grocery stores in low-income neighborhoods are less likely than stores in wealthier areas to carry healthy food choices such as fresh produce. People on limited incomes must feed their families with the cheapest and most readily available foods, which often are high in fat and calories. A possible explanation for this finding is that the eligible people who participate in the Supplemental Nutrition Assistance Program (SNAP) are in even greater need than income-eligible non-participants. This is generally attributed to selection bias -- low-income people are in the most need to apply for SNAP and similar benefits. Therefore, the finding can be explained by the differences in the initial nutrition status, not the effect of SNAP. In addition to lacking grocery stores, poor neighborhoods tend to have the highest density of fast food restaurants; for example, one study found that a large percentage of Chicago schools are within a short walk of a fast food restaurant.

Price, availability, and marketing drive people toward unhealthy foods, and higher calorie consumption follows because of snacking, soft drink consumption, and large portion sizes. But economic factors affect more than what people eat; they also affect how much people exercise. People with low incomes have less leisure time to be physically active. Many lack access to health clubs or exercise equipment, and they may have safety fears about their neighborhoods that keep them indoors.

If efforts to reduce obesity are to succeed, economic change is essential, as is attention to the price, accessibility, and marketing practices associated with both healthy and unhealthy foods. Obesity now costs the United States $190 billion a year, 20.6 percent of national health expenditures.

It is imperative that economists, who now are turning attention to the obesity problem, move beyond using economic principles to explain poor nutrition and obesity and begin helping in the search for creative ways to solve these major public health problems.