Fasting and metabolism
Researchers at the Okinawa Institute of Science and Technology and Kyoto University, working under the guidance of Professor Mitsuhiro Yanagida, identified 30 new compounds whose concentration in the body increases during fasting. These observations indicate that, in addition to weight loss, fasting stimulates metabolic activity, the synthesis of antioxidants, and also helps to eliminate a number of aging effects.
As part of the work, the authors analyzed the composition of whole blood, plasma and erythrocytes of four starving people and monitored changes in the levels of metabolites – compounds formed during chemical processes that supply organisms with energy and ensure their growth. As a result, 44 metabolites were identified, the concentrations of which increased 1.5-60 times in all participants during only 58 hours of fasting. 30 of these compounds have not previously been identified as being associated with fasting.
Previously, the authors identified a number of metabolites, the number of which decreases with age, including leucine, isoleucine and ophthalmate. The levels of these same metabolites increase in starving people, which indicates the possible existence of a mechanism by which fasting can increase life expectancy. Given the important roles of these metabolites in maintaining the functions of muscle tissue and the activity of metabolites, we can talk about the possible rejuvenating effect of fasting.
The results of the latest work of researchers indicate that a complete rejection of food, which puts the body into starvation mode, leads to a change of "fuel", a decrease in the production of free radicals, increased activation of mitochondria and a change in the mechanisms of signal transmission.
The human body, in order to obtain fast energy, strives to utilize carbohydrates, if they are available. With a lack of carbohydrates, he begins to consume other energy reserves. Switching to an alternative "fuel" leaves behind a trail of traces, namely metabolites such as butyrates, carnitines and branched chain amino acids. These well-known markers of energy source change accumulate during the fasting period.
However, apparently, the effects of starvation are not limited to changing the energy source at all. When conducting a comprehensive blood test of the study participants, the authors identified not only well-known markers of fasting, but also many other compounds. For example, a global increase in the concentrations of substances produced during the citric acid cycle was revealed, a process by which the body releases energy stored in the chemical bonds of carbohydrates, proteins and fats. A significant increase in the levels of these compounds indicates a heavy load on the mitochondria.
It also turned out that fasting activates the metabolism of purine and pyrimidine, chemical compounds that play key roles in the regulation of gene expression and protein synthesis. This fact indicates the ability of fasting to reprogram the profile of proteins synthesized by cells in a specific period of time, thus changing cellular functions. Such changes can contribute to maintaining homeostasis in cells or provide a change in gene expression in response to external factors.
The metabolism of purine and pyrimidine also increases the production of antioxidants in the body. It was found that the levels of certain antioxidants, including ergothioneine and carnosine, significantly increased during the 58-hour follow-up period of the study participants. The role of antioxidants is to protect cells from free radicals, which are byproducts of metabolism. The products of the metabolic mechanism known as the "pentose phosphate pathway" also neutralize the detrimental effect of oxidation, and their concentrations also increase during fasting, but only in blood plasma.
The authors suggest that these antioxidant effects may be the main reaction of the body to the cessation of nutrient intake, since starvation can lead to the formation of an oxidative internal environment dangerous for the body. The results of their exploratory study provided the first evidence in favor of the fact that antioxidants are a marker of fasting. In addition, the study gave rise to a new idea, according to which fasting can stimulate the production of a number of metabolites, synthesized in large quantities by the young body and absent in the old one.
The observations made by the authors confirm the already generally accepted ideas according to which fasting is beneficial for the human body. The next stage of the work should be the reproduction of the results obtained in a larger study or the search for alternative ways to trigger metabolic changes.
Article by Takayuki Teruya et al. Diverse metabolic reactions activated during 58-hr fasting are revealed by non-targeted metabolic analysis of human blood published in the journal Scientific Reports.
Evgenia Ryabtseva, portal "Eternal Youth" http://vechnayamolodost.ru based on materials from Okinawa Institute of Science and Technology (OIST) Graduate University: Fasting Ramps Up Human Metabolism, Study Shows.