Fasting as a religious ritual

Intermittent fasting has become very popular in recent years. Studies have shown various health benefits, including effectiveness in weight loss. Dry fasting is an extreme form of intermittent fasting, as it involves abstaining not only from solid food but also from liquids. One example of this is the religious Bahá'í fast. It is similar to the Ramadan fast, as it also starts before sunrise and ends after sunrise. The followers of the Bahá'í religion regard fasting as an important spiritual duty and fast for 19 consecutive days every year in March. The Bahá'í fast is performed when the days and nights are approximately the same length. This makes it a stable model for researching the effects of intermittent dry fasting.

Improved glucose metabolism

Time-restricted eating is another form of intermittent fasting that has become increasingly popular in recent years. It is characterized by a smaller time window of food intake, usually less than 10 hours per day, with varying timing and duration. Many studies show improvements in glucose metabolism, such as

the reduction of the mean 24-hour sugar level, and improved insulin sensitivity. However, it remains unclear whether intermittent religious dry fasting as a special form of intermittent fasting can trigger comparable effects on blood sugar or even have a negative effect.

It is known that people with diabetes who practice this form of fasting have an increased risk of hyperglycemia and hypoglycemia. What effects occur in people without diabetes has not yet been researched.

Three groups in comparison

Against this background, the team led by Prof. Dr. Olga Ramich investigated how religious fasting affects blood glucose control and variability in adults without diabetes and to what extent the effects differ from those of time-restricted eating. The pilot study involved 16 healthy men and women between the ages of 18 and 69. They were divided into three groups: Bahá'í fasting, intermittent fasting according to the 16:8 method or control group. The latter was allowed to pursue their usual diet without any time restrictions. During the initial start-up phase and during the 19-day intervention period, the participants' blood sugar levels were continuously monitored using a glucose sensor placed on the upper arm. In addition, the test subjects recorded their diet over the entire period.

No negative effects

When analyzing the data, the researchers found that although the Bahá'í fasting group consumed fewer calories per day and lost weight, there were no adverse effects on 24-hour blood sugar levels or glycemic variability. In the 16:8 intermittent fasting group, the average blood sugar level and variability also remained unchanged throughout the entire period.

“Our results suggest that both religious dry fasting and time-restricted eating can be safely integrated into the lifestyle of people without diabetes without compromising metabolic health,” says Prof. Dr. Olga Ramich, head of the Department of Molecular Metabolism and Precision Nutrition at the DIfE. If people with diabetes want to fast, they should first talk to their doctor, especially if they inject insulin. The doctor can help to adapt the treatment plan to ensure that their fasting will not cause any problems.

Metabolic flexibility as the key to success

The study underlines the metabolic flexibility of people without diabetes and shows that they can maintain stable blood sugar levels even with significant changes in dietary habits. This flexibility is a good prerequisite for effective weight management and improved eating habits. “Despite the promising results, further studies with larger cohorts are needed to confirm these findings and investigate the long-term effects of fasting on metabolic health,” says study coordinator and nutritionist Beeke Peters, who shares first authorship with Dr. Christina Pappe from the Charité – Universitätsmedizin Berlin.

Background information

Glycemic variability: Glycemic variability describes the fluctuations in blood sugar levels over time. It can be influenced by diet, age and physical activity, among other things. Continuous glucose monitoring (CGM) makes it easy to measure glycemic variability and detect fluctuations in the blood sugar profile. An ideal average blood sugar level within a day is of no advantage if the course of the glucose level is characterized by hypoglycemia and hyperglycemia. For example, blood glucose control within diabetes therapy is based on what is called “time in range” value between 70 and 180 mg/dL, which is the ideal range for glucose values. Continuous glucose monitoring also allows to determine other metrics that can be used to describe glycemic variability within a day and between different days. Glycemic variability is greater in overweight people and people with diabetes than in healthy adults.

Original publication:
Peters, B.*, Pappe, C. L.*, Koppold, D. A., Schipp, K., Arnrich, B., Michalsen, A., Dommisch, H., Steckhan, N., Pivovarova-Ramich, O.: Twenty-Four Hour Glucose Profiles and Glycemic Variability during Intermittent Religious Dry Fasting and Time-Restricted Eating in Subjects without Diabetes: A Preliminary Study. Nutrients 16(16):2663 (2024). [Open Access]  * geteilte Erstautorenschaft