A new study has investigated what happens when subjects consume a diet consisting only of ultra-processed foods (e.g. ready-made meals, sweet breakfast cereals, margarine, and ready-made desserts) for a certain period. Subsequently, it has been compared to what happens when the subjects only consume non-processed food for a similar period.
The study followed 20 healthy people over a period of four weeks, during which the subjects were assigned a customized diet of only ultra-processed foods for two weeks, and a diet of non-processed foods for a control period of another two weeks. The order of the weeks was randomly selected. The subjects were presented with portions measured in calories each time, so the availability was the same.
Large fluctuations in calorie intake
During the period where the subjects ate ultra-processed foods, they consumed on average 500 calories more a day than they did in the period where they did not eat processed foods. As a result, they gained one kilo after two weeks of eating ultra-processed foods, and vice versa, they lost one kilo during the two weeks where they did not eat processed foods.
A tempting conclusion of these results may be that you should eat fewer ready-made meals if you want to lose weight, but that is not necessarily the case. The degree of food processing between the two diets was not the only difference between them.
Is the obesity epidemic due to processed foods?
The development in the prevalence of type 2 diabetes and obesity across the world has been parallel to the development in the processing of food that is consumed. This does not mean that the processing of food itself is negative, but it is important to look at the composition of nutrition that exists in processed foods.
Ultra-processed foods often have a high energy density, which means they contain more calories per gram than what you would normally find in other foods. This also applies to the food products that the subjects in the study consumed and this difference is worth taking note of.
The study showed that the subjects consumed considerably more calories per minute when they ate the ultra-processed foods, which contained the most calories. This is also believed to have a significance because it takes some time before the body's sense of satiety sets in.
Ultra-processed foods are often made in such a way that they become hyper palatable. Hyper-palatable foods often contain a high level of both sugar, salt and fat, which triggers high levels of dopamine in most people and tempts for repeated intake of these foods.
A conclusion from this study matches all other studies that have investigated calorie intake, namely that if you consume fewer calories than you burn, you lose weight and vice versa. If anything were to be said about processed foods, it must be mentioned that it applies to ultra-processed foods that are energy-dense.
There are also ultra-processed foods that are not as energy-dense as in this experiment. Today, there is an increasing selection of salads and low-calorie alternatives that must be included in the study before anything can be said about ultra-processed foods in general.
Several diets may warn against processes foods without grounds
There are many different diets today that for many reasons recommend people to stay away from specific groups of foods. Common to several of these diets is that they warn against a high intake of processed foods.
The study that is discussed here points out that it has not previously been studied in so-called randomized and controlled intervention studies what effect processed foods actually have. Some of the studies, which the above-mentioned diets are based on, are observational studies in which the subjects have been self-reporting.
This means that a great deal of uncertainty is included in these studies, because it is not known what the subjects actually have consumed, and in many cases, the subjects also have to report the results themselves. In controlled intervention studies like this one, it is predetermined what the subjects should consume and this is followed up on with a control period to check for the impact of both the ultra-processed foods and the non-processed foods.