Abstract
As incomes rise, the share of income spent on food decreases. To Engel's law should be added the observation that the diet structure changes as well. Incomes and the macronutrient composition of the diet are linked at the aggregate and-most likely-the individual level. People in higher income nations consume more added sugars and fats than do people in lower income nations. Lower income consumers within rich nations consume lower-quality diets than do higher income consumers. The lowering of energy costs ($/MJ) through technological innovation has been most marked for foods containing added sugars and fat. Although wealthier persons in poor nations are more likely to be overweight, obesity in the United States is associated with lower incomes. Obesity in the United States and similar societies may be a socioeconomic, as opposed to a medical, problem and one that is related to diet structure and diet costs.
