Ultra-processed food is not good news anyway and often has higher levels of salt, sugar, fat, unnatural / poor ingredients, E numbers etc. although this was monitored so equal for the trial. They are also linked to cancer.
It is difficult to define ultra-processed food but most of us know it when we see it.
Things to look out for include:
More than five ingredients listed on the packet
ingredients you cannot pronounce
anything your grandparents would not recognise as food
enhancers such as flavourings, colours etc.
As part of the experiment 20 people volunteered to live in a laboratory condition for a month, eat as much as they wanted to and allowed every morsel of food they ate to be monitored. For the first two weeks they were given either ultra-processed food or unprocessed food and the following two weeks this was switched.
During the fortnight they had highly-processed food, they ate over 500 calories a day more and put on 2lb (1 kg) compared to when they were given unprocessed meals.
According to The US National Institutes of Health, ultra-processed foods may be affecting hunger hormones in the body, encouraging people to keep eating.
Dr Hall, from the National Institute of Diabetes and Digestive and Kidney Diseases, said: "This is the first study to demonstrate that there is a causal relationship.
"Ultra-processed foods led to increases in calorie intake and in body weight and in fat.
"It's suggestive that this may be playing a role in the larger population."
He said previous studies had estimated the "obesity epidemic" in the US was caused by people eating an extra 250-300 calories a day.
The volunteers said both meals were equally tasty, so a preference for ultra-processed food was not the reason.
The nutritional content of the two diets was also carefully matched to ensure they had equal amounts of sugars, other carbohydrates, fats and fibre.
One potential explanation is the impact of industrially processed foods on the hormones that alter the desire to eat.
Dr Hall explained: "When people were consuming the unprocessed diet, one of the appetite-suppression hormones (called PYY) that has been shown in other studies to be related to restraining people's appetite actually went up despite the fact that they're now eating less calories."
The study also showed the levels of the hunger hormone ghrelin went down on the unprocessed diet.
It does seem to be linked to the individual as well. The study was on a limited number of people and for a short time, so it is unclear if the findings apply more broadly.
Some people on the diet ate an extra 1,500 calories on the ultra-processed diet, while others ate roughly the same.
It seems that the volunteers found ultra-processed food more palatable, they ate it more quickly and consequently more as the ‘feeling full’ feeling lags behind.
One thing is for sure, you cannot beat unprocessed food if available, vegetables, fruit, grains, pulses and meat that are fresh with no added ingredients are still best.
All rights reserved. AR Pharmacy. Premises GPhC Number: 1043646