For years, experts have warned that packaged snacks, frozen meals, and sugary cereals aren’t doing our health any favors. Now, new evidence suggests that avoiding these ultra-processed foods—even those considered healthy—may lead to significantly more weight loss.
A clinical trial published in Nature Medicine found that participants shed nearly twice as much weight when they followed a diet made up of minimally processed foods, such as fruits, vegetables, chicken, yogurt, and whole grains. The research contributes to the growing concern about how heavily processed products affect metabolism, cravings, and overall calorie intake.
The main findings about ultra-processed foods and weight loss
The study, led by Samuel Dicken at University College London, followed 55 adults with body mass indexes in the overweight or obesity range. Most of them consumed diets high in ultra-processed foods before the trial began, similar to the average adult in the United States.
Researchers designed two eating plans. One relied mostly on minimally processed foods like oatmeal, plain yogurt, and home-cooked pasta dishes. The other centered on ultra-processed but nutritionally acceptable options, including plant-based milk, whole-grain cereals, frozen lasagna, and flavored yogurt. Both plans met official nutrition guidelines, limiting sugar, sodium, and saturated fat.
Participants spent two months on one plan, returned to their usual diet for a month, and then spent two months on the other. This crossover design allowed scientists to compare how each person responded to both approaches. On average, people lost about four pounds on the minimally processed diet, compared with just two pounds on the ultra-processed one.
When researchers projected those results over a year, the difference was striking: an estimated 9 to 13% reduction in body weight for the minimally processed diet, versus 4 to 5% for the ultra-processed diet. Participants also lost more than double the body fat when eating minimally processed foods.
Another important finding was how cravings and hunger played out. Many reported feeling greater control over their appetite and fewer urges to snack when sticking to whole, minimally processed meals. That pattern may help explain why their weight loss was more sustainable.
Ultra-processed foods and how to adapt your diet
Nutrition experts note that these findings align with previous research. Studies have shown that people naturally eat more calories per day when ultra-processed foods dominate their diets. These foods are often softer, easier to chew, and more calorie-dense, making it easy to eat quickly and past the point of fullness.
Still, avoiding them entirely is unrealistic for most people. They are cheap, convenient, and deeply ingrained in daily life. Experts recommend starting with small changes, such as cooking simple meals at home, choosing fresh or frozen produce, and selecting foods with short ingredient lists. Lean proteins, whole grains, nuts, beans, and vegetables are reliable staples that don’t require complicated preparation.
It’s worth noting that even in this trial, participants lost some weight on the healthier version of the ultra-processed diet. That suggests improvements can come from making better choices within the foods you already eat. But if weight loss and long-term health are the goals, the evidence strongly favors sticking with meals built around minimally processed ingredients.
