Chew on this

What if it’s texture that’s the big problem with ultra-processed foods?

Picture this:  You’re at an airport, and your food options are limited. The restaurant with the shortest line has two grab-and-go choices: 1) an egg sandwich and a smoothie combo and 2) a bagel with sliced chicken, cheese, and a side of fruit. The dishes have about the same number of nutrients and calories. But the egg sandwich breakfast is softer, and therefore easier to chew.

The texture, it turns out, may make a lot of difference.

In a study released last month, researchers demonstrated that people who ate ultra-processed foods with more texture ate more slowly and consumed significantly less. This was true across breakfasts and lunches for a variety of different meals: beef stew and mashed potatoes were gulped down more quickly than smoked sausage and sauerkraut; tortillas with ground meat, rice, and corn disappeared faster than a piece of chicken served with rice, corn, and French fries.  On average, study participants with “harder” foods ate 20 percent slower and consumed 11 percent less.

Why does this matter? Ultra-processed foods (UPF) are one of the hottest topics in nutrition. For the uninitiated, the easiest way to define ultra-processed foods are commercially manufactured products that include ingredients you won’t find in a home kitchen – think soda, frozen pizzas, instant ramen. (More details on the system of categorization can be found here.) 

Studies have shown that diets high in UPF are associated with obesity as well as heart disease and Type-2 diabetes. But exactly how and why UPF may be dangerous to our health is not yet clear.

Some believe it is the (many, many) additives in UPF that make them dangerous. Others worry high consumption of ultra-processed food can change the gut microbiota and lead to inflammation and chronic disease. Last month’s study is part of a research project called Restructure, which aims to discover whether something as simple as food’s texture may be the culprit.

It’s common sense that the speed of eating will affect how and when we feel full. It’s why, night after night growing up, my mother admonished me and my sisters: Eat slowly, girls! It is also logical that how food is packaged, so to speak, affects how many calories we consume. According to Restructure, an adult can consume a kilogram of grapes in just 1.5 minutes when it is squeezed into juice. In contrast, it takes 19 minutes – 12 times longer – to eat a kilogram of whole grapes, making it far more likely that the person will feel full before finishing the entire portion.  

In recent years, the growing controversy over ultra-processed foods has fueled new research into consumption patterns. The theory being: If we know that textures facilitate faster eating, then the effect will be even greater when the food is both packed with calories and designed to be eaten quickly. 

There have been a bunch of papers on this; among the most interesting is one from 2022  that looked at calorie intakes of “hard” and “soft”  minimally processed and ultra-processed foods. Study participants ate the harder foods more slowly than soft foods of either type. Ciarán Forde, the lead researcher at Restructure, has called soft, ultra-processed foods “effectively pre-chewed.”  

Softer foods do have some benefits, of course. The whole texture debate reminds me of a fascinating book I read (and reviewed for the Washington Post) by Harvard anthropologist Richard Wrangham: “Catching Fire: How Cooking Made Us Human.” 

In short, his argument goes like this: Humans’ ability to use fire to cook makes food more tender and easier to chew. This allowed early humans to eat more, develop a big brain, and, ultimately, reallocate hours of time spent eating to other pursuits. According to Wrangham, modern humans spend an average of just five percent of their time chewing – about 36 minutes in a 12-hour day. If we were still eating the diet of a great ape, we would need a whopping five hours a day to simply break down our food.

No one wants to go back to that. But, as in other realms, the industrial food system seems to have taken our human instinct for convenience much too far. We gain weight. They grow profits.

The good news is that we may soon have a definitive answer about the role of texture in UPF consumption. The Restructure project is at work on a randomized controlled study—the gold standard in research–to test how textures affect food intake. Results will be in by the end of the year.

Ciarán Forde, the lead researcher, told me in an email that if texture proves to be a significant driver of excess eating, it could “highlight a new way in which foods can be reformulated to change the way consumers interact with their food environment…[and] be a central component of efforts to improve the food supply and mitigate the risk of overconsumption.” 

I’m doubtful that food companies will jump at the chance to make foods that help us eat less. But I, for one, still am rooting for texture to be our next dietary villain. It’s easier to choose to eat harder foods (a crunchy granola bar) over a softer one (the chewy variety) than lobby food companies to give up their beloved and unpronounceable ingredients. And whether or not ultra-processed foods are a regular part of your diet, you can start trying to eat slowly right now.

Mom, as usual, was right.