Such people also tend to eat more quickly and consume more fats and carbohydrates, researchers say. “It’s not just the extra salt and fat in processed food that causes people to gain weight. It’s the processed food itself.”
People who eat a lot of highly processed food take in more calories and gain more weight than those who stick to a minimally processed diet, a new study conducted at the National Institutes of Health finds.
Many real-world studies of diet and nutrition rely on participants to remember what they ate, which is notoriously difficult for most people. The results of the study are published Thursday in the journal Cell Metabolism.
This project was much more controlled. A group of 10 men and 10 women lived at the NIH’s Clinical Center in Bethesda, Maryland, for 28 days, their meals provided by investigators with the National Institute of Diabetes and Digestive and Kidney Diseases.
For the first two weeks, half of the subjects ate what was called an “ultraprocessed diet.” That included foods many would regard as reasonable options: turkey bacon, chicken salad made with canned chicken, sweetened Greek yogurt, bagels with cream cheese and baked potato chips.
The other half stuck with a minimally processed diet, including meats and fish, whole fruits and vegetables, eggs, nuts and oatmeal. The second two weeks, participants switched diets.
“We found people over-ate on average more than 500 calories a day on the ultraprocessed diet,” study author Kevin Hall said. “They gained weight and gained body fat.”
Even though both diets were matched to have the same amount of calories, sugar, fat, fiber and macronutrients such as carbohydrates and protein, people gained about two pounds while eating the processed foods. And they lost about that much on the other diet.
It may be that people tended to eat more quickly and consumed more fat and carbohydrates on the ultraprocessed diet.
Dietitians say the results confirm what they’ve seen in studies. “Satiety is higher and longer lasting when we eat foods that have been minimally processed,” said Elisabetta Politi of the Duke Diet and Fitness Center in Durham, North Carolina.
