In Britain, experts estimated that fixing the country's bad eating habits might prevent nearly 70,000 people from prematurely dying of diet-related health problems like heart disease and cancer. It would also theoretically save the health system 20 billion pounds ($32 billion) every year.
In Brazil, however, the rates of illnesses linked to a poor diet are not as high as in the U.K. So Brazilians would get relatively few health benefits while their economy might lose millions.
The study was paid for by the London School of Hygiene and Tropical Medicine and was published online Thursday in the medical journal, Lancet.
"We are not suggesting people not eat a healthy diet," said Richard Smith, a professor of health system economics at the London School of Hygiene and Tropical Medicine. "We're just trying to point out that healthier eating can have unintended consequences."
Smith and colleagues said decisions in Brazil and in Western countries to adopt more vegetarian diets could cost the meat-dependent Brazilian economy 1,388 million reais ($815 million).
"In an ideal world, we would all have a perfect diet," Smith said. "But it's also desirable that everybody has a job."
Smith said officials should consider nutritional guidelines more carefully. For countries like Brazil, which rely heavily on meat imports to the West and to Japan, global nutritional advice could potentially be devastating.
Others weren't so sure.
"There are things happening in the rest of the world that this model didn't account for," said Julian Morris, executive director of International Policy Network, a London-based think tank. "The increasing demand for meat in Asia is substantial, ongoing, and might counteract any reduced demand in developed countries."
Morris also disputed the assumption that healthy eating recommendations would change what people actually do have for dinner.
"If you really want a dramatic change in consumption of meat and dairy products, you need a radical policy, like a tax or quota system," he said.
Robert Beaglehole, an emeritus professor at the University of Auckland not linked to the study, said scientific developments might help one day.
"The answer could be to breed healthier cattle and pigs," he said, adding that more research was needed on whether additional strategies were necessary to ensure healthy eating guidelines don't accidentally hurt developing economies.
Smith said experts shouldn't assume nutritional advice, even when it's followed, automatically improves health.
"You could tell people to buy less meat and maybe they will buy bananas instead," he said. "But they could also buy more beer and wine."