More money = more meat. In the U.S. and most of the Western world, that equation has held strong since the 1930s. But the math no longer adds up.

Meat consumption is dropping across Europe and now in the U.S. While still among the countries with the biggest meat appetites in the world, the U.S. Department of Agriculture reports meat eating in the U.S. is on the decline, three decades after health concerns first started denting demand for beef. After peaking at 184 pounds per person annually in 2004, Americans now eat an estimated 167 pounds today, according to the Earth Policy Institute, an environmental think tank, with consumption at its lowest level in more than a decade. (This is boneless weight for beef, chicken, turkey, and pork rather than the higher estimates that include whole carcasses).

In the developing world, the correlation between money and meat is strong.

The trend is driven by a number of factors. Rising prices have hit people’s pocket books. Demand is shifting away from expensive cuts, and so companies are increasing exports overseas where consumption is booming. The decades-long drumbeat of health warnings from doctors and health agencies have also had an impact. All of this is drawing praise from advocates of healthier diets that go easier on the planet: obesity, degraded ecosystems, and greenhouse gas emissions are all exacerbated by modern meaty diets and the factory farms that feed them.

Yet in the developing world, history is repeating itself. From Brazil to China, growing wealth had fed a voracious appetite for fat and protein, most of it from livestock (typically at the expense of tubers, cereals, and other plants that compose traditional diets in poorer counties).

That’s, of course, good news for many countries where malnutrition and growth stunting remains a problem. But it also spells trouble for global health of people and the planet.

Around the world, more than a third of adults are now overweight or obese, up from 23% in 1980. Most of the super-sizing has occurred in the developing world, reports the Overseas Development Institute (ODI), a U.K. think tank that focuses on development and humanitarian issues. Although meat-heavy diets are not solely to blame, the rising incidence of some cancers, diabetes, heart disease, and strokes are all correlated with excessive fat consumption and obesity.

This growth is eventually expected to taper off. For now, however, in the developing world, the correlation between money and meat is strong. In China, increases in income almost exactly track rising meat consumption, reports the ODI.