As Donald Trump’s administration throws sharp elbows in trade negotiations and systematically rescinds regulations introduced by Barack Obama, one casualty is likely to be efforts to fight the global obesity epidemic. Left unchecked, rapidly rising obesity rates could slow or even reverse the dramatic gains in health and life expectancy that much of the world has enjoyed over the past few decades. And by forcing its food culture on countries like Mexico and Canada, the United States is making the problem worse.

One of the paradoxes of modern global capitalism is that whereas more than 800 million people in the world do not have enough to eat, an estimated 700 million people (including 100 million children) are obese. Of course, the two are not necessarily directly related. A considerable proportion of world hunger occurs in countries suffering from domestic strife or severe government dysfunction.

The obesity epidemic, however, has a much broader footprint, affecting advanced economies and most emerging markets. Although there is some connection between obesity and poverty within countries, it is notable that obesity rates in rich countries such as the United States, the United Kingdom and Canada are among the world’s highest.

Recently, the US Centers for Disease Control estimated that a stunning 40% of all Americans are obese (defined as having a body mass index of 30 or higher), a figure that includes 20.6% of adolescents (12-19 years old). According to the CDC, the average weight of an American woman today is greater than the average weight of an American man in 1960 (166 pounds, or 75 kilos).

Back in 1960, the average weight of an American woman was 140 pounds, while the average weight of an American man today is 195 pounds. (Over the same period, the average height of Americans increased by only one inch, or 2.5 centimetres.) This same dynamic is playing out worldwide, with obesity rates soaring in Europe, Latin America and even in China.

Although it is difficult to gauge the long-run health consequences, there is abundant evidence that obesity contributes significantly to higher rates of type 2 diabetes, heart attacks and certain types of cancer. The health costs are staggering, estimated to be close to $200bn per year in the US alone. And with rising childhood obesity rates worldwide portending significantly greater health problems in the future adult population, the costs are likely to rise considerably.

The causes of obesity are manifold and complex. Nevertheless, a growing body of evidence suggests that a culture emphasising processed food and a generally sedentary lifestyle lies at the centre of the problem. In emerging markets, rapid urbanisation is another important factor, as well as a desire to emulate western lifestyles.

Many governments have launched initiatives to improve nutrition education. Unfortunately, industry advertising typically dwarfs these efforts, as do US trade lobbyists’ own efforts to push processed and fast food on the rest of the world.

It is hard to ignore the fact that Mexico’s adult obesity rate has soared since the adoption in 1993 of the North American Free Trade Agreement. While there are many causes, post-Nafta direct foreign investment in the processed food industry and a surge in advertising are important contributors.

Mexican consumption of sugary beverages nearly tripled between 1993 and 2014, and a new tax on sugary drinks has muted demand only slightly since then. The other Nafta partner, Canada, has similarly experienced a rise in obesity, partly because US imports have led to a sharp decline in the price of fructose.

It is unfortunate that government regulators have been so slow to try to reverse these trends by, for example, helping to educate the public on the science of nutrition. And, for too long, most government anti-obesity education has focused on mechanically regulating calorie intake, without taking into account that different foods have dramatically different effects on appetite (as David Ludwig, a professor at Harvard Medical School, emphasises in his excellent new book Always Hungry).

Sceptics may point out that nutrition guidelines always seem to be morphing, with last year’s sin food becoming this year’s superfood, and vice versa. Though there is some truth to this, the fact is that nutrition research has made significant progress in recent decades.

The government has other tools at its disposal, besides education, for affecting people’s eating habits. They can and should place greater restrictions on advertising to children, as the UK, France and several other countries have done; obesity in early years can lead to lifelong problems. Beyond that, Ludwig, Tufts University’s Dariush Mozaffarian and I have proposed instituting a tax on processed food, much the same way that tobacco is taxed. Proceeds from the tax could be used to subsidise healthier alternatives.

It is perhaps fantasy to expect the current US administration to consider any kind of anti-obesity strategy while it is still busy dismantling Obama-era policies. But that is all the more reason why countries entering new trade agreements with the US (for example, the post-Brexit UK, or post-Nafta Canada) must be wary of any provisions that tie their hands in the war against obesity.

• Kenneth Rogoff is professor of economics and public policy at Harvard University. He was the chief economist of the IMF from 2001 to 2003.