New research shows people lose more weight eating minimally processed food rather than ultra processed food, even when the two diets are nutritionally matched.
A trial involving 55 people saw the group split into two.
One group followed an eight-week diet of minimally processed food, which included meals like homemade spaghetti bolognese.
This was followed by a ‘washout’ four weeks where the group ate as normal, then they switched to a diet of ultra processed food, which included meals like lasagne ready meals. The other group followed the same diets but in reverse order.
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Both diets were nutritionally matched according to the UK government’s Eatwell Guide, so they were the same in terms of levels of fat, saturated fat, protein, carbohydrate, salt and fibre, and recommended intake of fruits and vegetables.
Both groups lost weight but the key finding was the weight loss was greater (2.06% reduction) on the minimally processed diet compared to the ultra processed diet (1.05% reduction).
First author Dr Samuel Dicken, from the University College London (UCL) Centre for Obesity Research, said: “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.
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.
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“The primary outcome of the trial was to assess percentage changes in weight and on both diets we saw a significant reduction, but the effect was nearly double on the minimally processed diet. Though a 2% reduction may not seem very big, that is only over eight weeks and without people trying to actively reduce their intake. If we scaled these results up over the course of a year, we’d expect to see a 13% weight reduction in men and a 9% reduction in women on the minimally processed diet, but only a 4% weight reduction in men and 5% in women after the ultra-processed diet. Over time this would start to become a big difference.”
Study author Professor Chris van Tulleken, from UCL Division of Infection and Immunity, added: “The global food system at the moment drives diet-related poor health and obesity, particularly because of the wide availability of cheap, unhealthy food.
“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 on to the environmental drivers of obesity, such as the influence of multinational food companies in shaping unhealthy food environments.”
Read more in Nature Medicine.
