What are the rationale for fasting?

Diet: what is the real benefit of fasting?

Most people think that we need good food in order to be productive - which cannot be dismissed out of hand. But the renouncement of sweets, alcohol, meat or other foods practiced by many people during Lent does not have to do any harm to well-being; the opposite is often the case. Around every tenth German citizen therefore states that they skip one or the other delicacy for several weeks during Lent after Ash Wednesday. Therapeutic fasting cures are also enjoying increasing popularity - almost all year round: After all, the body should "purify", as it is said so nicely with an actually meaningless word. Five questions, five answers on the keyword "fasting".

1. Fasting: religion, tradition or fashion?

In today's affluent society in particular, as a countermovement to the food that is always available, renunciation is back in vogue. The wide range of therapeutic fasting offers in more or less reputable facilities is evidence of this. But fasting has a longer history than any fashion wave and has its origins in religion. In the Asian region in particular, it has been integrated into Buddhism, Hinduism and Jainism for thousands of years. The goal of the procedure here is spiritual purification. Indians of North American tribes, on the other hand, used it in the pursuit of visions for their further life. Fasting also has its place in Judaism and Islam.

During the Christian Lent, some foods such as meat, dairy products and eggs are usually banned from the menu. Today, however, a number of new traditions have developed from this religious requirement, such as the renouncement of stimulants such as alcohol and tobacco or a renunciation of non-material kind such as media consumption.

A historical adjustment to nutrient-rich and nutrient-poor phases in the annual cycle as the reason for Lent is obvious. Some researchers assume that our body is evolutionarily oriented towards this and that the constant availability of food and regular meals throughout the day, as we know them, are not biologically "normal" (PDF). Fasting for religious or traditional reasons contrasts with the therapeutic effect. But how can a body living in deficiency recover from illness? The Medical Association for Therapeutic Fasting and Nutrition therefore defines fasting as the voluntary avoidance of solid food with a calorie intake of less than 500 calories (in the form of broth and juice), usually over a period of 7 to 28 days.

2. How long can the body go almost without food?

In 2010 the film "In the Beginning Was Light" caused a sensation. Different people reported that they lived on "light food", so they did not consume liquid or solid food - which of course is scientifically unsustainable. A healthy body can, depending on its constitution, get along for four weeks or more, depending on the stored fat reserves, without solid food, provided that sufficient vitamins and minerals are absorbed in liquid form. However, our organism can only compensate for foregoing water for a few days.

First of all, fasting means stress for the body, as it has to switch from the usual diet to the body's own reserves. A sign of this is the initially increased release of the hormones adrenaline, noradrenaline, dopamine and cortisol. However, the values ‚Äč‚Äčnormalize after a while, and then the receptor sensitivity even increases sustainably: the body becomes more receptive to such signals.