Periodic fasting is a popular diet to lose weight and maintain weight, among other things.

In a new American study, researchers wanted to see what effect the method has on weight loss and blood pressure. 

"We have long wondered if the time a person eats affects weight, no matter how many calories a person eats," says Nisa M. Maruthur, a medical researcher at John Hopkins University in Baltimore who is the lead author of the study. 

Researchers who have previously tried to investigate it have not checked the number of calories.

So it has been difficult to determine whether the result is due to a change in time or the number of calories, says Nisa N. Maruthur.

- In this study, the only thing we changed was the time when the participants ate.

The study lasted twelve weeks

In the study, all participants ate exactly the same healthy food every day for twelve weeks.

But half the group ate for a limited time early in the day and the other spread out during the day.

The analysis showed that people in both groups lost weight and had lowered blood pressure - regardless of when they ate. 

- We thought that those who ate for a limited time would lose more weight.

But it did not happen.

Both groups lost about the same amount of weight.

We also saw no differences in blood pressure, says Maruthur.

Mai-Lis Hellénius, professor of cardiovascular prevention at Karolinska Institutet, thinks it is an interesting study, even though it is small. 

- It is an exciting and current issue because it is so popular with periodic fasting. 

Blood fats increase by eating late

One half of the group ate a large part of the calories in the evening, but still lost no less weight.

Mai-Lis Hellenius points out that it can still be a risk to eat late - for the blood fats.   

- If you eat the same thing as you eat during the day at night, then you get a little higher blood fats.

This is because you do not sell them directly.

If you take a brisk walk after a heavy meal, then you can halve your blood fats, Mai-Lis Hellènius explains.

One shortcoming she points out in the study is that the participants only followed the diet for twelve weeks and she does not think that one should pull too big gears on an individual, relatively small study because lifestyle changes take a long time to implement. 

But lead author Nisa N. Maruthur explains that it is difficult to get test subjects to participate for longer than twelve weeks with this type of regulated eating at the millimeter level.

- We know from previous weight loss studies that participants reach a peak in weight loss at three to six months, so we think that twelve weeks was still long enough to be able to see an impact on weight. 

Obesity prevention best weapon

Obesity researcher Erik Hemingsson at GIH is not surprised by the results of the study.

He says that there is not much research that supports the hypothesis that time-limited intake of food has an effect on weight loss. 

- When it comes to obesity, prevention is our best weapon because obesity is a very difficult condition to treat.

He points out that obesity is primarily due to socio-economic factors and the stress it causes with, among other things, high cortisol levels in the body, in combination with our modern lifestyle.

He strongly advises against working with his weight. 

- If you are a person who is doing and yo-yo dieting, that is, is doing and forcing your weight, then you risk in the long run getting rid of important muscles and thus get lasting negative changes in your metabolism.

Erik Hemingsson strikes a blow for living healthy and being overweight.

- You can eat well, exercise, sleep well, stress less, have social capital that is incredibly protective against ill health.

You can be a bit overweight but it does not have to mean much in terms of health. 

The study was published in the American Heart Association.