There is a great irony of 21st-century global health: While many hundreds of millions of people lack adequate food as a result of economic inequities, political corruption, or warfare, many hundreds of millions more are overweight to the point of increased risk for diet-related chronic diseases. Obesity is a worldwide phenomenon, affecting children as well as adults and forcing all but the poorest countries to divert scarce resources away from food security to take care of people with preventable heart disease and diabetes.

To reverse the obesity epidemic, we must address the fundamental causes. Overweight comes from consuming more food energy than is expended in activity. The cause of this imbalance also is ironic: improved prosperity. People use extra income to eat more and be less physically active. Market economies encourage this. They make people with expendable income into consumers of aggressively marketed foods that are high in energy but low in nutritional value, and of cars, televisions set. And computers that promote sedentary behavior. Gaining weight are good business. Food is particularly big business because everyone eats.

Moreover, food is so overproduced that many countries, especially the rich ones that far more than they need, another irony, than the United States, to take an extreme example, most adults—-of all ages, incomes, educational levels, and census categories—are overweight. The U. S. food supply provides 3800 kilocalories per person per day, nearly twice as much as required by many a-dults. Overabundant food forces companies to compete for sales through advertising, health claims, new products, larger portions, and campaigns directed toward children. Food marketing promotes weight gain. Indeed, it is difficult to think of any major industry that might benefit if people ate! Less food; certainly not the agriculture, food product, grocery, restaurant, diet or drug industries. All flourish when people eat more. And all employ armies of Lobbyists to discourage governments from doing anything to inhibit overeating.

The great irony of 21st century global public health refers to______.