When stepping into the grocery store a consumer might be greeted by a wall of fresh fruits and vegetables, they might even wander through the dairy aisle, but eventually, inevitably, they will be inundated by the bright wrappers of ultra processed foods before they check-out. A new study in the May 16 edition of “Cell Metabolism” revealed that consuming foods like these can lead to weight gain of up to two pounds per week.

It seems like common sense to avoid foods high in calories, but a the new paper implies that foods like candies, soft drinks and prepackaged dinners do more than pile on the calories. At the National Institutes of Health (NIH) scientist Kevin Hall and others performed a highly controlled study to determine how these ultra processed foods influence weight gain.

20 participants stayed at the NIH for four weeks and agreed to have their diets controlled by researchers. The volunteers were given meals of either whole foods, foods that have not had colors or preservatives added, or ultra processed foods. After two weeks the diets switched, so that those receiving the “healthy” foods were provided with “unhealthy” foods. Participants were allowed to eat as much as they wanted of their given meal, but could only consume the foods provided by the research team. The foods were specifically designed to comtain the same about of sugar, fat and fiber in both the processed and unprocessed meals. Individuals ate nearly 500 extra calories per day while on the ultra processed diet. These extra calories predictably led to weight gain.

The study adds a new element to the saga of obesity in America because it suggests that something about ultra processed foods leads to physiological changes that promote overeating. Previously, researchers believed that the extra calories contained in ultra processed foods were solely to blame. Hall, the principal investigator from the National Institutes of Diabetes, Health and Kidney Diseases explained that initially, “I was skeptical we would see any difference in how many calories people ate.”

While the results of the study were dramatic, many questions remain unanswered. Not all individuals responded to the processed diets in the same way. Some overate by more than 1,500 calories, while others consumed the same amount of food. The sample size was too small to determine what factors contribute to these different responses. To better understand the complex interactions between processed foods an individual’s genetic makeup, background and eating habits, researchers will eventually need a larger sample size and more complex experiments.

This May, Harvard Health Publishing released a report on work published in “Journal of the American Medical Society, Internal Medicine.” The study was not as highly controlled as the work at the NIH, but did provide a much larger data set based on people’s everyday lives, not four weeks spent in a controlled setting. This work utilized data from nearly 45,000 adults.

The participants were asked to self report their calorie and food-type intake through various nutritional assessments. The average person consumed 15 percent of their daily calories in the form of ultra processed foods. The team found a direct correlation between the amount of ultra processed food consumed and risk of death by cardiovascular disease and cancer. From a 10 percent increase in caloric intake from ultra processed foods, participants saw their risk of cancer diagnosis increase by more than 10 percent.

These findings provide strong support that reducing ultra processed food consumption may help address the complex factors contributing to rising obesity rates. This research adds new data to the debate on resistricting acess to ultr processed foods. Before any potential legislative decisions are made, researchers have determined several ways for consumers to promote their own well-being. While the research is innovative, the message is the same: swap out the starbursts for some starfruit.