Scientists have learned what happens in the body if you don't eat for a week
An international group of researchers analyzed the changes that occur in the human body if you completely eliminate food intake for seven days.
Humans are able to go without food for quite a long time - this evolutionary adaptation has been developed over thousands of years. In both ancient and modern societies, prolonged fasting has been practiced around the world for medical purposes to treat diseases such as epilepsy or rheumatoid arthritis. Today, abstinence from eating is more often used for weight loss, but what happens to the body is still not quite clear. One thing is clear - during prolonged fasting, the body switches to absorbing calories from its own fat reserves.
Scientists from the universities of Berlin Medical (Germany), Aarhus, Copenhagen (Denmark), Norwegian School of Sports Sciences, Oslo University Hospital (Norway) decided to learn more about this issue and conducted an experiment involving 12 volunteers (five of them were women, seven were men). The scientists' findings were published in the journal Nature Metabolism.
Participants did not take food for seven days - they were given only water. All this time, their health was monitored most carefully, recording changes in the level of about three thousand proteins in their blood. Protein tests were also taken from the participants before and after the fasting period.
As expected, the volunteers' bodies switched energy sources from glucose to internal stores during the first two to three days of fasting. Interestingly, it was mostly the participants' muscle mass that melted during this time, not their fat deposits. The total weight loss for all seven days of the experiment averaged 5.7 kilograms.
At the same time, scientists observed how in the body of volunteers there are distinct changes in protein levels after about three days of fasting - the body was clearly responding to stress. Until then, the researchers did not observe any special changes in the participants' bodies, that is, it happened later than expected.
In general, one in three of the proteins analyzed by scientists in all subjects underwent significant changes during fasting in all major organs. Among other things, the scientists found that fasting contributed to major modifications of the brain-specific extracellular matrix protein tenascin-R. This protein plays a role in neurite growth, nerve cell adhesion and modulation of sodium channel function, and is a component of perineuronal networks.
"For the first time, we were able to see what happens at the molecular level in the body when people give up food. Starvation, if done safely, is an effective means of weight loss. Not only is interval fasting, which is popular today, believed to not only help weight loss, but it is also believed to have health benefits. We confirm that fasting is indeed beneficial, but this effect becomes noticeable only after three days of complete restriction of any calorie intake into the body," said one of the authors of the study, Claudia Langenberg from the Medical University of Berlin.