Same Healthy-Eating Targets, Slightly More Weight Loss on Less-Processed Food

CATEGORY: DIET & WEIGHT

When two eating patterns both follow national healthy-eating guidelines, the one built mostly from minimally processed foods was linked to about twice as much weight loss as one built from ultra-processed foods over eight weeks. That is the headline from a 2025 randomized trial in which the same people tried both approaches, and it points to something surprising: how your food is made may matter for body weight even when the nutrition on paper looks the same.¹

Both Menus Met the Same Nutrition Targets

Ultra-processed foods are items assembled largely from industrial ingredients and additives rather than whole foods you would recognize in a kitchen—think mass-produced packaged breads, reconstituted meats, flavored snacks, and sweetened drinks. Minimally processed foods are whole or lightly handled foods, such as fresh fruit, plain yogurt, eggs, and home-cooked grains. The important twist in this study is that both menus were designed to meet the same official nutrition targets for things like fat, sugar, salt, and fiber. The only major difference was the degree of processing.

Fifty Adults Ate Each Diet for Eight Weeks

Researchers used a crossover design, meaning each participant served as their own comparison. Fifty adults ate a minimally processed diet for eight weeks and an ultra-processed diet for eight weeks, with a four-week break in between so one phase would not bleed into the next. Both diets were matched to the United Kingdom’s national healthy-eating guide, and food was provided to the participants so the researchers could hold nutrition steady while varying only processing. The difference in percent weight change between the two diets was the trial’s prespecified main outcome, and it favored the minimally processed menu.¹ Body weight was recorded on a calibrated scale, and body composition—how much of that weight is fat versus other tissue—was measured with a standard clinic device. Because people rotated through both diets, the design helps rule out the possibility that one group simply had an easier time to begin with.

About 2% of Body Weight Lost Versus 1%

On the minimally processed diet, participants lost about 2% of their body weight; on the ultra-processed diet, they lost about 1%.¹ In other words, the minimally processed pattern was associated with roughly double the weight loss over the same eight weeks—a difference of about one percentage point of body weight. In weight terms, the minimally processed diet was linked to about 0.96 kilograms more loss than the ultraprocessed diet.¹ The reductions in fat mass and in visceral fat, the fat packed around your internal organs, reached statistical significance only on the minimally processed diet. Participants also reported better control over cravings during that phase. These are modest amounts over two months, not dramatic transformations, but they moved consistently in the same direction.

Physical Form of Food May Nudge Body Weight

The takeaway is not that ultra-processed food is off-limits or that either diet was “bad”—both followed healthy guidelines and both were linked to some weight loss. Rather, the trial suggests that the physical form of food, how quickly it is eaten, and how strongly it drives cravings may nudge body weight independently of the nutrition label. This was a small, short study, so the findings are best read as an early signal rather than the final word, and researchers have since published follow-up discussion of the results. Still, it adds to a growing body of work suggesting that leaning toward less-processed versions of foods you already enjoy may be associated with better weight and cravings outcomes.

Japanese Men Gained About 1 Kilogram More

Other research points the same way. In a randomized crossover study, Japanese men with overweight gained about 1 kilogram more body weight during a week of ultra-processed meals than during a matched week of whole-food meals, and chewed their food less.² A review pooling studies of nearly 10 million people found those with higher ultra-processed intake were more likely to have obesity, though such studies track what people already eat and cannot show cause.³

Key Takeaways

• Over eight weeks, a mostly minimally processed diet was linked to roughly twice the weight loss of an ultra-processed diet, even though both met the same healthy-eating targets.
• The effects were modest and came from a small, short trial, so they are an early signal rather than a guarantee of results.
• Both diets met the same healthy-eating targets, so the difference tracked with how processed the foods were rather than with nutrition on paper.

References

1. Dicken SJ, Jassil FC, Brown A, et al. Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial. Nature Medicine. 2025;31(10):3297–3308. link
2. Hamano S, Sawada M, Aihara M, et al. Ultra-processed foods cause weight gain and increased energy intake associated with reduced chewing frequency: a randomized, open-label, crossover study. Diabetes, Obesity and Metabolism. 2024;26(11):5431–5443. link.
3. Lane MM, Gamage E, Du S, et al. Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. BMJ. 2024;384:e077310. link.