A new Lancet report on this "Double Burden of Malnutrition" says that never before have these two debilitating nutrition issues - undernutrition and obesity - been so commonly found together in the same country, home, or even person. But that's exactly what's happened "due to very rapid changes in the food system."

Much of the problem stems from the global availability of processed foods. These foods, which have been accompanied by skyrocketing obesity rates in rich and middle income countries for decades, are now traveling into the homes of some of the world's poorest people.

They are making everyone fatter, but not necessarily more full of nutrients. And they have health consequences for generations of mothers and their babies.

"The quality of the food is absolutely poor," said Francesco Branca, the World Health Organization (WHO) Director of the Department of Nutrition for Health and Development, on a call with reporters. "So, not enough vitamins and minerals, and cheap food, high in fat, sugar and salt."

Kids who are stunted may be overweight at the same time, while some obese mothers now give birth to babies who are wasting before age 5, the report found. Children from shantytowns in Brazil are growing bellies even as they're suffering from stunted growth and have little lean mass.

The long-term consequences of these ills are well known. Being overweight or obese can lead to health problems like type-2 diabetes, high blood pressure, and heart disease. It's also linked to strokes, cancer, and pregnancy issues. Undernutrition early on can set people up for more serious health issues later in life, as it can have long-lasting effects on a person's microbiome, metabolism, and insulin-signaling pathways. A kid who's stunted early on is more likely to put on belly fat when they're older, which is one of the most dangerous kinds of flab for overall health.

These health issues come at a high cost to society at large. At least 8% of global GDP is lost due to malnutrition, and another 3% is lost because of issues related to people being overweight, according to the WHO. Bad diets are also responsible for about one of every five adult deaths globally, the report finds.

Processed foods are bad for our hearts, waistlines, and future generations

Processed foods can make people eat more, eat faster, and get hungrier more often. As these foods become available and affordable to more people around the world, they also become at risk for a set of health issues that results from both from not getting enough nutrients and from eating lots of sugary, processed junk food. 

"The food environments that are shaping around the world, indeed in turn shape the nutrition of generations," Alessandro Demaio, one of the report authors and the former CEO of the EAT-Lancet commission, said on the call, adding that the "globalization, the commodification, and the homogenization" of our global food systems contribute to this new reality.

Branca says the effects are felt across the world, especially in areas of Latin America, sub-Saharan Africa, and Southeast Asia. He mentioned Botswana, Zimbabwe, Egypt, and Mongolia as examples.

The report focuses on 10 potential solutions to this bad, cheap food crisis, related to education, policy reforms, and changes in the global food system.

"I admit that it's not an easy job, because the influence of the food industry is an important one," Branca said.

Healthy diets filled with fresh fruits, vegetables, whole grains, nuts, and beans, would go a long way towards easing the problem. Taxes on processed foods and sugary drinks; incentives for community food production; and reformulation of food products would also help, the report said.

But flawed marketing is also a major issue. The report suggested that, for this reason, policy makers should "eliminate the promotion of breast milk substitutes," and "reduce the marketing of foods, snacks, and beverages high in energy, sugar, fat, and salt," while at the same time, regulators also need to get better at policing overblown health claims from food manufacturers.

"By focusing only on addressing under-nutrition and food insecurity for so long ... interventions have actually allowed or, have not prevented foods high in fat, sugar, and salt to move center stage," said Corinna Hawkes, a report author and professor at the University of London's Centre for Food Policy, on the call. "We must find ways to address both under-nutrition and obesity at the same time."