Proper fasting promotes the balance of our metabolism, known as homeostasis, and triggers the process of autophagy, a cellular recycling programme. Tobias Eisenberg explains: "Defective components are broken down. Their remains serve as building blocks for new functional components. This promotes cell repair." At the same time, ketone bodies are produced as a by-product of fat burning. They replace sugar as an energy source and in turn promote autophagy. Eisenberg tested this effect on himself: "What fascinated me during my several-day fasting regimen was the disappearance of the feeling of hunger. After two to three days, I experienced a surge of energy that felt like a relaxed endurance run."
By abstaining, you put your body in an exceptional situation. "We are not only investigating how fasting changes energy metabolism, but also whether and how it delays cell ageing," says Eisenberg. "Studies on model organisms such as flies, nematodes and mice show that this can work." In the Cluster of Excellence MetAGE, funded by the Austrian Science Fund (FWF), the researcher is investigating these processes with colleagues from the Medical Universities of Graz and Vienna. And what is the best method of fasting? Even the molecular biologist cannot answer that question. "There are too few good comparative studies with humans."
Risks
Eisenberg points out the dangers of food deprivation: "Without calorie intake, a person will eventually die. Our organism is not capable of obtaining energy from light; we do not photosynthesise." The molecular biologist also warns against extreme forms of fasting. "In addition to the possible benefits, there are also risks such as malnutrition or undernourishment." A permanent reduction in calorie intake of more than 30 percent can be harmful. Children, adolescents, pregnant and breastfeeding women, as well as elderly and sick people should not fast, or only do so under medical supervision. "The most important thing is to listen to your own body," advises Eisenberg. "What is good for one person's health may be harmful to another."