So how do you get people to drink more soda?

That's a question Coca-Cola and other soda makers are wrestling with as soda drinking has waned in U.S. and European markets.

In the 2010s, Coke made a big push into rural parts of lower income countries to sell more soda. So they made smaller, more durable bottles – a 1-cup serving size that could be sold more cheaply and last longer on the shelves.

They built solar-powered coolers that allowed sellers to keep Coke bottles cold in places off the electrical grid – and offer mobile phone-charging to their customers.

And they launched "splash bars" – small businesses run by women that sold shots of Coke, Fanta and other Coca-Cola products for as low as 7 U.S. cents a serving to make the beverage affordable to everyone.

The company presented this strategy as a win-win – they benefited because their product was becoming more available in remote areas and female entrepreneurs had a new way to earn a living.

That's a story that Eduardo J. Gómez tells in his new book. As he points out, Coke's characterization of a win-win isn't universally embraced.

Gómez, director of the Institute of Health Policy and Politics at Lehigh University, says Coca-Cola is one of many junk food companies – fast-food giants like McDonald's and KFC – who are targeting "emerging economies" – countries where income is on the rise along with trade with wealthier nations.

In these countries, many people see the ability to buy so-called junk food – not just soda but packaged chips and candies and fast food from chains – as a sign they're made it. And the junk food manufacturers try to put a positive face on their campaigns to expand their audience. They forge partnerships with local governments to fight hunger and poverty – even as the rising consumption of junk food leads to soaring rates of obesity and diabetes.

In his new book, Junk Food Politics: How Beverage and Fast Food Industries Are Reshaping Emerging Economies, Gómez describes a two-way street, where industry and political leaders work together to launch well-meaning social programs – but also skirt regulations that would harm industry's profits. The result, Gómez says, is that junk food industries thrive in low resource countries at the expense of children and the poor, who develop long-term health problems from consuming sugar-laden, ultra-processed foods.

NPR spoke with Gómez about junk food barges, soda taxes and why healthy eating campaigns aren't cutting it against ads for candy and fried chicken. The conversation has been edited for length and clarity:

Let's start with an easy question. What is junk food?

I define junk food as highly ultra-processed fast foods, from KFC to burgers, candies, confectionery, ice cream. Junk food is also Coca-Cola, Pepsi, Mountain Dew – high-sugar, carbonated soda drinks.

What role does junk food play in lower- and middle-income countries?

There's a proliferation of these junk foods now, not only in cities but in rural communities in India, in Mexico, even into the Brazilian Amazon.

In the emerging economies, these foods that were not [previously] accessible suddenly became very accessible in the 1990s or early 2000s.

We're seeing [a vast and rapid] infiltration of these foods because of what I call "fear and opportunity." "Fear" that industries have of losing market [share] in Western nations, and "opportunity" because there's a [growing] middle class in these emerging economies that are eager to purchase them.

What is junk food politics?

Junk food politics is a two-way street. It's when [junk food] industries influence politics and society so they can avoid regulations that will impact their profitability, such as taxes on junk foods and regulations on marketing and sales.

We often think industry is to blame. But governments are also to blame [because political leaders partner with industry on their own political agendas – which gives industry clout to undermine policies that would cut their profits].

What's a good example of junk food politics in action?

In Brazil, for example, you have the rise of industry groups, [like the Brazilian Food Industry Association] that were very, very influential in lobbying the congress and infiltrating national agencies that are working on regulations [like advertising restrictions for junk food]. They're engaging in partnerships [with governments and communities where] they can be perceived as a solution to the problems [of obesity and diabetes] by, for instance, helping to improve the [sharing] of nutritional information. They're building legitimacy and avoiding costly regulations.

At the same time, [Brazil's] President Lula [in his prior term] had a famous anti-hunger campaign. And Lula worked with Nestlé to strengthen this program and went as far as creating an office within his presidential palace to partner with industries that wanted to contribute to this anti-hunger program. And so that was a strategic, two-way partnership that benefited industry and benefited the government.

Of course, President Lula's intentions were admirable in alleviating hunger. But perhaps it wasn't a good idea to partner with companies that produce a lot of these ultra-processed foods, because it indirectly legitimizes the company. It amplifies the popularity of their products and their harmful consequences to health.

As low-resource countries rise in wealth, rates of obesity and diabetes also tend to rise. What is the scope of the problem? Why does it happen?

The incidence of childhood obesity is growing much faster in developing countries [than in the West]. [Rates of] type 2 diabetes among adolescents are extremely high in India and China and Mexico.

The rural poor are also becoming obese and getting diabetes. This is something we don't normally assume. In India, for example, in the 1990s and early 2000s, obesity was seen as a "disease of luxury." It was perceived that only people with status and money that could go to fast food establishments were having this problem. For many years the government didn't do anything because they perceived [growing rates of diabetes and obesity] as affecting a small minority of the population.

But now, it's become a general issue because of the increased access to junk foods.

How has access increased? How did junk foods go from being concentrated in cities to being common food items in rural places?

[Junk food distribution] started in cities, and over time they [expand] out to other areas of the country. In Brazil, for a while, Nestlé had these large blue Nestlé boats that traveled throughout the Amazon and distributed candy and cookies throughout the Amazon. [The "junk food barges," as critics called them, have stopped]. In rural India, there are shops where people pay for one small shot of Coca-Cola while getting their phones charged.

In every country, junk food is something that's voluntarily bought. It's voluntarily eaten. So why are programs that encourage healthy eating and daily exercise and nutrition labeling not enough to convince people to avoid it?

Of course we want people to have nutritional information – we want people to know more, and we want them to know what they're eating. And there's growing commitment and success on better food labels. Chile, for example, has introduced more effective food labels – on products high in salt, sugar and fat, they have adopted these black octagon images that are on the food products – that have rippled out through the Americas.

But people are always flooded with marketing and access [to processed foods]. Even when you have this knowledge, there are incentives for you to eat these products that are readily available and less healthy.

What I hear you saying is that healthy eating and exercise campaigns focus on the individual, but poor health and nutrition are rooted in bigger, systemic problems.

Yes, absolutely. Nutritional information is very important, but it's insufficient. We need to address socioeconomic factors, marketing factors, all these things that play into [making junk foods an easy, accessible choice].

You say governments in low-resource countries have made some progress on taxing junk foods and improving the labeling. What else do you think needs to happen?

None of these governments have committed to restricting advertising. [Countries have, instead, relied on voluntary pledges from companies to refrain from marketing unhealthy foods to children.] In a lot of these countries, there are no firm laws on what can be sold in schools. And even when they have laws or rules that prohibit the sale of junk foods in schools, they are not effectively being enforced.

There's a paradox: While countries [such as Mexico, Brazil, India and Indonesia] have done a great job of increasing nutritional awareness, obesity and diabetes is still skyrocketing. And that's because governments are doing a little bit on the fringes but not really getting to the heart of the problem. They're not taking on these industries through regulations to sales and advertising.

What does junk food politics cost society?

There's an extremely high cost to society, mainly from the health consequences. If you develop type 2 diabetes as a consequence of high sugar intake, it has a tremendous impact on your quality of life. Argentina, for example, has seen a crisis in the affordability of insulin. In the context of global universal health care, we don't pay enough attention to ensuring that the poor do not go broke in getting the medicines that they need to address their high blood pressure, their [blood] sugar.

What's the solution? What can cut into the influence that junk food politics has on public health?

The solution is having a government that is committed to ensuring the health of all of society. One that provides activists and communities with a voice that is equal to, or exceeds, the voice of industries within government. One that has no fear of taking on the powerful industries and creating regulations that protect vulnerable populations – especially children and the poor – over the interests of major corporations.

And the solution, too, is our work in communities as researchers and as community members, to raise the awareness about the importance of good nutrition and exercise, and to increase awareness about the need for access to healthier foods.

And just wondering if climate change will play any role?

That's the topic of my next book – climate change and malnutrition.

And your thesis is that with the changing climate ...

... the availability of healthy foods becomes increasingly scarce.