Cutting out processed food helps weight loss

Eating a diet based on minimally processed homemade food can help you lose twice as much weight compared with munching ultra-processed snacks and meals. Food is usually ranked as ultra-processed if it contains ingredients not or rarely used in kitchens, for example additives including flavourings and thickeners and high-fructose corn syrup.

Multiple studies have demonstrated adverse health outcomes from ultra-processed diets such as type 2 diabetes and weight gain. Ultra-processed food also tends to be higher in salt, sugar or fat. A debate arose as to whether it was these ingredients per se that harmed health or whether the processing itself was more the culprit.

To gain a better understanding here, Scientists at University College London asked 55 overweight or obese people to eat either a diet of ultra-processed or minimally processed fare. Both groups were given food worth about 4,000 calories and were told to eat as much as they liked. The ultra-processed diet included foods such as breakfast cereals, chicken sandwiches, protein bars and ready-made lasagnes but versions low in fat and salt. The minimally processed diet featured homemade food such as overnight oats, bread made from scratch, spaghetti bolognese and chicken salad.

Both diets resulted in weight loss, by 2 per cent for the minimally processed regime and just 1 per cent for the ultra-processed diet. Persons on the minimally processed diet also saw higher fat loss in body tissue, particularly in muscles, and in the blood, along with a greater reduction in cravings. For control purposes, after four weeks the groups switched diets with those eating ultra-processed food switching to a minimally processed diet and vice versa. After a month the same result was observed, with those eating minimally processed food again losing more weight than the other group.

Other studies have also shown that consuming the same amount of calories in a minimally processed diet as in an ultra-processed one can result in greater weight loss or less weight gain. One international team of scientists even discovered that a diet high in ultra-processed foods introduces higher levels of pollutants that are known to affect sperm quality. 

Ultra-processed foods undergo industrial processes such as hydrogenation and moulding, while containing other additives such as dyes, stabilisers, flavour enhancers, emulsifiers and defoaming agents.

Higher levels of microplastics have also been detected in ultra-processed foods. This is widely believed to be because of the more machinery the material has to pass along.