Abstract
Undernutrition--protein energy malnutrition or specific nutrient deficiencies--has been an inherent characteristic of impoverished populations throughout the world. Over-nutrition, obesity and nutrition imbalance is a current concern among those with rising though still insufficient incomes. We review data to suggest that the prevalence of these forms of malnutrition in populations is highly influenced by the rate of appearance of discretionary income. In developed countries, discretionary (alternatively "disposable") income refers to funds available after obligate payments (rent, heat, and the cost of getting to work) and payment for necessities (food and clothing). For families living at or below poverty, the last dollar earned is spent on these obligations. Undernutrition is common. By contrast, likelihood for obesity or imbalance increases with rising income when that last dollar is earned without certainty that it is available for discretionary spending. In the United States, neither under- nor over-nutrition is likely when new income is free and clear of debt or obligation. This occurs at approximately three times the poverty level. While income poverty and food insecurity affect risk for malnutrition rather than outcome, nutrition education programs that address issues of income and food support increase likelihood for adherence to recommendations.