A recent UCL study found that participants lost twice as much weight on a minimally processed diet compared to an ultra-processed diet, with significant improvements in health markers, suggesting broader dietary shifts could combat obesity and improve overall health.
A pioneering clinical trial conducted by researchers at University College London (UCL) and University College London Hospitals (UCLH) has found that diets composed of minimally processed foods lead to significantly greater weight loss compared to ultra-processed food diets.
Published in Nature Medicine, this trial represents the first of its kind to compare the effects of these diets under real-world conditions over an extended period.
In this study, 55 adults were divided into two groups and given nutritionally matched diets based on the UK’s official dietary guidelines, the Eatwell Guide.
The participants alternated between eight-week periods of minimally processed food (MPF) diets — such as overnight oats and homemade spaghetti Bolognese — and ultra-processed food (UPF) diets, like breakfast oat bars and ready-made lasagne.
“Previous research has linked ultra-processed foods with poor health outcomes. But not all ultra-processed foods are inherently unhealthy based on their nutritional profile,” first author Samuel Dicken, from the UCL Centre for Obesity Research and UCL Department of Behavioural Science & Health, said in a news release. “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.”
Significantly, after eight weeks, participants on the MPF diet experienced a 2.06% reduction in weight, compared to a 1.05% reduction on the UPF diet. This difference translates to an estimated calorie deficit of 290 kilocalories per day on the MPF diet versus 120 kilocalories per day on the UPF diet.
The weight loss on the MPF diet primarily came from reductions in fat mass and total body water, indicating a healthier body composition.
The study also analyzed participants’ food cravings, finding that those on the MPF diet showed a two-fold greater improvement in overall craving control compared to those on the UPF diet.
“The global food system at the moment drives diet-related poor health and obesity, particularly because of the wide availability of cheap, unhealthy food,” added co-author Chris van Tulleken, from the UCL Division of Infection & Immunity and UCLH. “This study highlights the importance of ultra-processing in driving health outcomes in addition to the role of nutrients like fat, salt and sugar. It underlines the need to shift the policy focus away from individual responsibility and onto the environmental drivers of obesity, such as the influence of multinational food companies in shaping unhealthy food environments.”
While the study primarily focused on weight loss, it also examined various secondary health markers, such as blood pressure, heart rate and blood markers related to liver function, glucose, cholesterol and inflammation.
Although there were no significant negative impacts of the UPF diet on these markers, the researchers caution that longer-term studies are needed to fully understand these effects.
“Despite being widely promoted, less than 1% of the UK population follows all of the recommendations in the Eatwell Guide, and most people stick to fewer than half,” added senior author Rachel Batterham, from the UCL Centre for Obesity Research.
“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. 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.”
The research underscores the complex relationship between food processing, weight management and overall health, and suggests that dietary policies should consider the degree of food processing in addition to traditional nutritional metrics.
Source: University College London