How Ultra-Processed Foods Could Cause Disease: Changes in Texture

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All prospective population studies to date on ultra-processed food consumption and weight gain have found that the more ultra-processed foods people eat, the more likely they are to become overweight or obese. Why might that be the case? One of the reasons people tend to over-consume ultra-processed foods more than less-processed foods may be a change in texture.

If you feed people a so-called soft rice salad made with creamy risotto rice and boiled vegetables, they end up eating 17%more calories than when given the same salad made with regular rice and raw vegetables. Even just swapping a hard hamburger bun for a soft one can make a difference. However, this is the opposite of what Big Food tends to dish out for us. The food industry processes products for maximum consumption rate. They don’t call it fast food for nothing. As opposed to those made in a factory, foods that grow tend to be slow. Thanks in part to the fiber content of whole, healthy plant foods, the default eating rate of more healthful foods just tends to be slower naturally.

Though there are certainly exceptions, like caramel toffee, highly processed foods tend to be consumed quicker. There can be a hundredfold difference in consumption between the fastest and the slowest foods. You could consume an entire two-thousand-daily-calorie-allotment’s worth of chocolate milk in four minutes, whereas it would take more than six straight hours to chew through that many raw carrots.

Based on this particular sampling of 45 foods, though, it doesn’t look like ultra-processed foods are consumed any faster than less processed foods. But based on an analysis of hundreds of different foods, the average caloric intake rate of ultra-processed foods is about double that of unprocessed foods––but note that’s in calories per minute. Maybe that has less to do with the eating rate, and more to do with how concentrated in calories so many ultra-processed foods are, often packed with added sugar and fat, not to mention salt and flavor enhancers to help trigger compulsive eating. How could we tease out all these factors?

In a landmark study, people were assigned, in random order, a diet composed of either ultra-processed foods or unprocessed foods for two weeks. But here’s the kicker: the diets were matched for presented calories, carbs, protein, fat, sugar, salt, and fiber. So, if the reason people overeat ultra-processed foods is not the degree of processing, but rather their junky nutrient profile, then this should have evened things out. But no, they averaged 500 more calories each day on the ultra-processed diet. So, they ate about 500 more calories a day, and gained about a pound (0.45 kg) a week, while those on the unprocessed diet lost about a pound a week. So, within two weeks, there was already a four-pound (1.8 kg) difference between the two groups.

So, despite the ultra-processed and unprocessed diets being matched for daily presented calories, sugar, fat, fiber, and macronutrients, people consumed more calories when exposed to the ultra-processed diet as compared to the unprocessed one. And had the experimental diets allowed for the greater differences in sugar, fat, and salt that you typically see in ultra-processed foods, you can imagine how the weight gain would have been even worse. So, limiting consumption of ultra-processed foods may be an effective strategy for obesity prevention and treatment.

But since the researchers matched sugar, fat, and salt in the two diets, why did people overeat the ultra-processed foods? It’s not because the ultra-processed foods were significantly more delicious; the diets were successfully matched for palatability too. What differed was eating rate. People were consuming calories 50% faster on the ultra-processed diet compared to the unprocessed diet. And we know that the faster we eat, the more calories we tend to take in, presumed to be because our natural satiety mechanisms don’t have time to catch up. However, there are two other reasons explaining why people gained so much more weight eating the ultra-processed diet, which I’ll cover, next.

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• Mambrini SP, Menichetti F, Ravella S, et al. Ultra-processed food consumption and incidence of obesity and cardiometabolic risk factors in adults: a systematic review of prospective studies. Nutrients. 2023;15(11):2583.
• Astrup A, Monteiro CA. Does the concept of “ultra-processed foods” help inform dietary guidelines, beyond conventional classification systems? NO. Am J Clin Nutr. 2022;116(6):1482-1488.
• Bolhuis DP, Forde CG, Cheng Y, Xu H, Martin N, de Graaf C. Slow food: sustained impact of harder foods on the reduction in energy intake over the course of the day. PLoS One. 2014;9(4):e93370.
• de Graaf C, Kok FJ. Slow food, fast food and the control of food intake. Nat Rev Endocrinol. 2010;6(5):290-293.
• Viskaal-van Dongen M, Kok FJ, de Graaf C. Eating rate of commonly consumed foods promotes food and energy intake. Appetite. 2011;56(1):25-31.
• Forde CG, Mars M, de Graaf K. Ultra-processing or oral processing? A role for energy density and eating rate in moderating energy intake from processed foods. Curr Dev Nutr. 2020;4(3):nzaa019.
• Hall KD, Ayuketah A, Brychta R, et al. Ultra-processed diets cause excess calorie intake and weight gain: an inpatient randomized controlled trial of ad libitum food intake. Cell Metab. 2019;30(1):67-77.e3.

Motion graphics by Avo Media

• carrots
• fat
• hamburgers
• junk food
• milk
• obesity
• salads
• sugar
• Ultra-Processed Foods