Ready meals encourage the appetite

Lisa Vogel studied departmental journalism with a focus on medicine and biosciences at Ansbach University and deepened her journalistic knowledge in the master's degree in multimedia information and communication. This was followed by a traineeship in the editorial team. Since September 2020 she has been writing as a freelance journalist for

More posts by Lisa Vogel All content is checked by medical journalists.

Ready meals are considered fattening. They are often particularly rich in calories. But that's only half the problem: They also appear to increase appetite.

Ready-made lasagne, frozen pizza and instant soups are quick to prepare, inexpensive and are therefore increasingly being put on the plate. But a US study now shows that highly processed foods actually stimulate you to eat more and thus promote weight gain.

Ready meals against fresh food

A team led by Kevin Hall from the National Institutes of Health recruited 20 adults for their experiment. They were on average 31.2 years old and slightly overweight with an average BMI of 27.

All participants lived and ate in the laboratory during the four-week study period. Half of them were served ready meals three times a day for two weeks. On the first day, for example, honey cereals with milk and a muffin were on the breakfast table. A portion of canned ravioli followed at lunchtime and steak with mashed potatoes and corn in the evening.

The second group was only served unprocessed, freshly prepared meals. On the first day there was Greek yoghurt with fruit in the morning, a salad with spinach and chicken breast for lunch and steak with broccoli in the evening.

Differences in detail

As different as the ready-made and fresh food menus were, the portions matched in terms of calorie density, sugar and salt content, as well as fat and fiber content. However, they differ in the details: in the amount of added sugar, the amount of insoluble fiber and the saturated and unsaturated fatty acids. The ready meals also contained a little less protein.

The subjects had one hour for their meals and were allowed to eat as much or as little as they wanted. After two weeks, all participants were prescribed the other nutritional program.

Processed foods stimulate the appetite

The result: If the participants were served ready meals three times a day, they ate faster and ate more than the fresh food group. On average, they ate 500 kilocalories more every day. Accordingly, they put on an average of 0.9 kilograms during this time. If the participants then ate fresh food for two weeks, they lost 0.9 kilograms.

"I was surprised," says study director Hall. "I thought that if the two diets contained the same components, we would find no magical effect of the highly processed foods on appetite." In fact, the opposite was the case.

Less protein, more hunger

At least in part, the lower amount of protein in the convenience food might explain the differences in calorie intake. Because protein is a filler. Those who eat low-protein ready-made meals may therefore have to eat more overall until they feel full.

But other components of the finished food could also fuel the appetite - for example unhealthy fats, high fructose corn syrup, flavorings or emulsifiers.

Avoid highly processed foods

"This is the first study that actually shows that highly processed foods stimulate people to eat more calories and gain weight," said Hall. "Limiting the consumption of highly processed foods could be an effective strategy for being overweight to avoid or treat, ”the researchers write.

However, this is easier said than done: "We have to consider that it costs more time and money to prepare products with little processing," says the researcher. "Simply telling people to eat healthier is enough for people who have little access to have healthy food, is not enough.

4.75 billion for pizza & Co.

Ready meals are more popular than ever in Germany: In 2018, Germans spent 4.75 billion euros on frozen pizzas and the like, and the trend is rising. In 2013 it was 3.88 billion euros.

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