Fasting can help boost metabolism: study

Tokyo: Occasional fasting can not only help people lose weight, but also boost their metabolic activity, generate antioxidants and reverse some of the effects of aging, according to a study. Scientists from the Okinawa Institute of Science and Technology (OIST) and the Kyoto University in Japan have identified 30 previously undeclared substances, the amount of which increases during fasting and indicates various health benefits.

"We have been studying aging and metabolism for many years and have decided to look for unknown health effects in human fasting," said Takayuki Teruya, lead author of the paper in Scientific Reports. "Contrary to initial expectations, it has turned out this fast-induced metabolic activation rather actively," Teruya said.

The study presents an badysis of total human blood, plasma and red blood cells collected from four fasted individuals. Researchers have monitored the evolution of metabolite levels – substances formed during chemical processes that give energy to organisms and allow them to grow.

The results revealed that 44 metabolites, 30 previously unknown, increased universally in subjects 1.5 to 60 times in just 58 hours after fasting. In previous research, researchers have identified various metabolites whose amounts decrease with age, including three known as leucine, isoleucine and ophthalmic acid. In fasted individuals, the level of these metabolites increases, suggesting a mechanism by which fasting may help increase longevity.

"These are very important metabolites for maintaining muscle and antioxidant activity, respectively," said Teruya. This result suggests the possibility of a rejuvenating effect by fasting, which was not known until now, "he said. The human body tends to use carbohydrates to produce quickly energy – when they are available.When the body lacks carbohydrates, the body begins to loot its alternative energy reserves.

The act of "energy substitution" leaves a trace, including metabolites called butyrates, carnitines and branched chain amino acids. These well-known markers of energy substitution have been shown to accumulate during fasting. However, fasting seems to produce effects far beyond the substitution of energy. In their comprehensive badysis of human blood, researchers noted both established fast markers and many others. For example, they found an overall increase in substances produced by the citric acid cycle, a process by which organisms release energy stored in the chemical bonds of carbohydrates, proteins and lipids.

The marked increase suggests that during fasting, the tiny central cells of all cells are submerged.
Fasting also appears to improve the metabolism of purine and pyrimidine, chemicals that play a key role in gene expression and protein synthesis.

The discovery suggests that fasting can reprogram which proteins the cells build at what time, thus altering their function. The change can promote homeostasis in cells or serve to alter the expression of their genes in response to environmental influences. The results develop well-established ideas about what fasting could do for human health. The next step would be to replicate these results in a larger study or to study how metabolic changes might be triggered by other means.