Cutting processing, not nutrition, may double weight loss success
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In a new UCL-led trial, people eating minimally processed foods lost twice as much weight as those on ultra-processed diets even though both meals were nutritionally matched.
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The study used a randomized crossover design: participants spent eight weeks on one diet, had a four-week washout, then switched allowing each person to serve as their own control.
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Diets followed the UKs Eatwell Guide, ensuring both processed and less-processed meals were balanced but the level of processing still made a big difference.
A new, real-world experiment shows that simply eating less processed food might help you drop those extra pounds even when your meals are supposed to be equally healthy.
The study compared two diets that looked the same on paper but one was made up of fresh, minimally processed meals, and the other packed with store-bought, ultra-processed versions.
The results? The less processed menu won the weight-loss race and by a big margin.
Previous research has linked ultra-processed foods with poor health outcomes, researcher Dr. Samuel Dicken said in a news release. But not all ultra-processed foods are inherently unhealthy based on their nutritional profile.
The main aim of this trial was to fill crucial gaps in our knowledge about the role of food processing in the context of existing dietary guidance, and how it affects health outcomes such as weight, blood pressure and body composition, as well as experiential factors like food cravings.
The study
Researchers from University College London recruited 55 adults in England. They all had body mass indices between 25 and 40 and habitually ate more than half of their calories from ultra-processed food.
They split participants into two groups: one started eating minimally processed meals things like homemade spaghetti Bolognese or overnight oats for eight weeks. After a four-week wash-out returning to their normal diet, they switched to the ultra-processed diet (like breakfast oat bars or ready-meal lasagne).
The other group did the diets in the opposite order. Both menus followed the UK Eatwell Guide, so calories and nutrients were carefully matched including red flags like sugar, salt, and overall balance.
Results: Twice the weight loss, same nutrients
Heres the bottom line: even though both diets were thoughtfully designed to be healthy, the minimally processed diet led to twice the weight loss compared to its ultra-processed counterpart. Thats not just a little double the effectiveness.
This matters because it shows processing level itself not just calories or nutrients can influence weight loss.
So, if youre looking for a simple, practical way to boost your results, cooking at home and swapping processed convenience foods for fresh alternatives could be a surprisingly powerful move.
The best advice to people would be to stick as closely to nutritional guidelines as they can by moderating overall energy intake, limiting intake of salt, sugar and saturated fat, and prioritizing high-fiber foods such as fruits, vegetables, pulses, and nuts, researcher Professor Rachel Batten said in a news release.
Choosing less processed options such as whole foods and cooking from scratch, rather than ultra-processed, packaged foods or ready meals, is likely to offer additional benefits in terms of body weight, body composition and overall health.
Posted: 2025-08-11 18:19:00