Ultra-processed foods expand waistlines, study finds

Washington — Eating a diet of mostly ultra-processed foods can lead to higher calorie consumption and weight gain, according to the results of a recent study.

For the study, researchers from the National Institutes of Health enlisted 20 adult volunteers (10 men and 10 women) to eat a 14-day diet of ultra-processed foods – those containing ingredients such as high-fructose corn syrup, hydrogenated oils, flavoring agents and emulsifiers – followed by 14 days of eating meals made up of minimally processed foods, or vice versa.

The participants were given three meals a day and allowed to eat as much or as little as they liked. All the meals contained the same amount of calories, macronutrients, sugar, fiber, fat and carbohydrates. However, compared with the minimally processed meals, the ultra-processed meals contained higher amounts of added sugar than total sugar (54% vs. 1%, respectively), insoluble fiber than total fiber (77% vs. 16%) and a larger ratio of omega-6 fatty acids than omega-3 fatty acids (11-to-1 vs. 5-to-1).

Participants following the ultra-processed diet showed a greater energy intake, with increased consumption of fat, sodium and carbohydrates, but less protein. Researchers found that weight changes “were highly correlated with energy intake.”

These results show a “clear and consistent difference between the two diets,” lead study author Kevin D. Hall, a senior investigator at the National Institute of Diabetes and Digestive and Kidney Diseases at NIH, said in May 16 press release.

Added NIDDK Director Griffin P. Rodgers: “Over time, extra calories add up and that extra weight can lead to serious health concerns. Research like this is an important part of understanding the role of nutrition in health and may also help people identify foods that are both nutritious and accessible.”

Although the researchers note that the study reinforces the benefits of unprocessed foods, they acknowledged that avoiding processed foods can be more expensive and time-consuming. The weekly cost of preparing a 2,000-calorie-a-day diet of unprocessed foods was estimated to be $151, compared with $106 for a diet of ultra-processed foods.

“Just telling people to eat healthier might not be effective for some people without improved access to healthy foods,” Hall said.

The study was published online May 16 in the journal Cell Metabolism.