Metabolic breaks in sync: This is how intermittent fasting works
Intermittent fasting encompasses various methods aimed at deliberately restricting daily eating times . The idea behind it: your metabolism shouldn't be constantly working, but should also be allowed to take a break. Unlike traditional fasting regimens, where food is abstained from for extended periods, intermittent fasting integrates the respective fasting periods flexibly into everyday life. Intermittent fasting also scores points for its simplicity, as there are hardly any rules to follow apart from the eating times. This makes the concept so attractive and practical for everyday life . You alternate between phases of eating and fasting, whether daily or several times a week. Crucial to success is the regular rhythm , which helps your body adapt to the changes and achieve the desired effects.
Intermittent fasting and classic calorie deficit compared
Earlier, smaller studies suggested that intermittent fasting might have positive effects on weight loss. However, one of the most comprehensive studies on this topic—the 2018 HELENA study by the German Cancer Research Center and Heidelberg University Hospital—revealed interesting results: Intermittent fasting is just as effective at weight loss as a conventional diet that maintains a daily calorie deficit. Over a 12-week period, overweight participants in both groups lost approximately 20% of their weight. However, metabolic improvement was no greater with intermittent fasting than with the traditional diet, and even after one year, there were no significant differences between the two groups.1
The good news for you: Both intermittent fasting and maintaining a calorie deficit without time restrictions generally work for weight loss and can also help you maintain your ideal weight in the long term. But what other benefits can fasting offer?
Fasting is believed to support the body's detoxification processes . To understand why this is beneficial, let's look at what happens in your body after a meal. Once you've eaten, your body enters the so-called " postprandial state ," which lasts for about four hours. During this time, your body digests the food, hormone levels rise, and fat storage is activated. Other processes, such as the immune system, take a back seat.²
All of this is normal, but it also demands a lot of effort from your body. The problem? While snacking between meals was hardly common until the 1980s, today we consume an average of three meals plus two snacks per day . For our bodies, this means that instead of 8-12 hours, they now spend around 20 hours a day in a postprandial state.³
Why are meal breaks so important?
Our body is relieved when it is not in a postprandial state. Only then does it switch into a A kind of cleanup mode (known as autophagy ). In this process, damaged cells are broken down, pathogens are eliminated, and the entire system is purified.⁴ It is even believed that autophagy could play a crucial role in preventing diseases such as cancer, diabetes, and autoimmune diseases.⁵ Furthermore, fat burning is activated during this phase, instead of fat being stored.⁴
If you eat constantly, your body gets used to drawing energy from these meals instead of relying on stored fat reserves.
Longer breaks between meals , on the other hand, give your body the opportunity to recover and optimize important metabolic processes . However, it is not yet scientifically clear exactly when this natural cleaning process begins – some experts suspect that autophagy starts after 12 to 16 hours, while others believe that it only begins after 72 hours without food.
Further research suggests that intermittent fasting is particularly healthy precisely because it reduces or eliminates evening and nighttime food intake, thus extending the overnight fasting periods. This can lead to lasting health improvements.⁶ Improved sleep patterns , promoted by longer nighttime fasting intervals, could in turn lower cortisol levels, which can contribute positively to weight loss . Studies show that every three-hour extension of the nighttime fasting window is associated with lower blood sugar levels (HbA1c) and lower inflammatory markers in the blood (CRP). In contrast, shorter nighttime eating breaks are often associated with higher blood sugar levels and less sleep. Although studies are still limited, this data supports the idea that earlier daytime eating and extended nighttime fasting could reduce the risk of common chronic diseases.⁷
Intermittent fasting could indeed have some positive effects on our health. But which methods are currently particularly popular and how promising are they really?
16:8 Intermittent fasting: Probably the most popular method
A particularly popular option for beginners is the 16:8 method, in which you fast for 16 hours and eat within the remaining 8 hours . This can make it easier to achieve a calorie deficit, but it's no guarantee of success if you eat more than your calorie needs during the 8-hour eating window.