Many nutrition experts blame processed foods for the obesity epidemic, suggesting that a return to home cooking would turn it around. But some researchers are pushing back against that idea, arguing that it oversimplifies the obstacles that poor and middle-class families face.

A flurry of studies have provided new evidence that these foods, which are typically loaded with salt, sugar, fat and chemical additives, heighten the risk of obesity and chronic disease.

Scientists at the National Institutes of Health found that people ate more calories and gained weight on a diet of mostly ultra-processed foods like frozen entrees, diet beverages, fruit juices, pastries, baked potato chips, canned foods and processed meats. A pair of large studies in the journal BMJ showed that people who ate significant amounts of these foods had increased mortality rates and cardiovascular disease compared to people who avoided them.

These findings and others prompted health experts to urge Americans to limit their intake of ultra-processed foods. But highly processed foods have become the dominant food source for many Americans, accounting for almost 60% of our calories. Americans across the socioeconomic spectrum consume them in increasing amounts. Many households depend on them because they are cheap, convenient and, in some cases, their only option.

Sociologists Sarah Bowen, Joslyn Brenton and Sinikka Elliott — who wrote “Pressure Cooker: Why Home Cooking Won’t Solve Our Problems and What We Can Do About It” — studied 168 poor and middle-class families in North Carolina, a state where 1 in 3 adults is obese and 1 in 10 has diabetes. They followed the families for up to five years and spent hundreds of hours with some.

Their research challenges the idea that Americans can reclaim their health and reverse the obesity epidemic if only they would ditch processed foods and make healthy meals from scratch. While that will work for some people, Bowen and her colleagues argue that it is not a realistic solution for families that have limited time and money.

Nor is it necessarily an accurate perception: National surveys show that 48% of Americans cook dinner six or seven nights a week, and 44% cook two to five nights a week. The data show that low-income families spend more time cooking than wealthier families, and they consume less fast food than middle-class households.

But the researchers found that many families faced an array of obstacles to healthy eating. Some of the families they studied lived in food deserts, far from a decent grocery store, and had to spend hours riding a bus to buy groceries or ask friends and relatives for a ride. Many would run out of money at the end of the month and look for ways to stretch what little food they had. Some did not have reliable stoves and refrigerators, or they lacked basic kitchen tools. Others turned to their local food pantries, which provide a lot of processed foods that are shelf-stable.

With so many hurdles in their way, the researchers found, working class families would often shy away from foods that cost more and spoil quickly, and instead turn to things that they could cook easily, store for a long time and stretch into numerous meals.

“If you’re strapped for cash and running out of food every month like a lot of families did in our study, the cheapest thing you can buy is ramen, hot dogs, and boxed macaroni and cheese,” Bowen said. “We asked everyone in our study what would you buy if you had more money to spend on food, and the most common answer was: ‘Fresh fruit for our kids.’ ”

According to federal data, about 15 million U.S. households suffer from food insecurity, meaning they do not have enough food to meet their needs.

There are no easy answers. But the researchers say what is needed are policies that better support families, like universal child care, paid parental leave, universal free lunch programs at school, a higher minimum wage and sick leave.

“The bottom line of what we found is that families are stretched thin and they’re up against a lot,” Elliott said. “Our big message is that if we really value healthy families, then we need to figure out ways to support them.”