Why Does Intermittent Fasting Prolong Life?
What are all the benefits of fasting? Stimulates cellular autophagy, extends lifespan, and improves metabolism. So what are the benefits of intermittent fasting on a molecular level ?
On January 3, the Salk Institute for Bi ological Studies republished a study in the journal Cell Metabolism .
The results of the study show that intermittent fasting promotes longevity in mice by altering gene expression throughout the body. In other words, through intermittent fasting, genes can be affected to provide life extension and reduce the risk of disease.
Fasting Alters Gene Expression in Mice to Extend Lifespan
On January 3, the Salk Institute for Biological Studies published a study in the journal Cell Metabolism.
Mice were fed either isocaloric feeding (ALF) or TRF (time-restricted feeding) at random and gene expression changes were analyzed in samples of 22 organs and brain regions of the mice collected every 2 hours for 24 hours.
The researchers found that TRF profoundly affected gene expression throughout the body of the mice.
To obtain the relatively early transcriptional changes associated with TRF time-restricted feeding in mice, the researchers gave 12-week-old C57BL/6J mice either short-term ALF isocaloric ad libitum feeding or TRF ( time-restricted feeding) for seven weeks, restricting food to a nine-hour daily feeding window.
Both groups were fed the same amount of food, and as a result, the ALF mice showed abnormalities such as weight gain, obesity and metabolic dysfunction, while the TRF time-restricted feeding mice showed no abnormalities.
The researchers then executed the mice every 2 hours for 24 hours .
Twenty-two brain regions and surrounding tissues were collected and quickly frozen within 1 hour of collection.
→TRF Induces Rhythmicity in Global Gene Expression and Functional Pathways
Seven weeks later, researchers collected tissue samples from 22 organ groups and the brain of mice at different times of the day or night and analyzed for genetic changes.
(The samples included tissue from different parts of the liver, stomach, lungs, heart, adrenal glands, hypothalamus, kidneys, and intestines, as well as from different regions of the brain.)
As a result, the researchers found that in the mice, 70% of the genes responded to time-restricted eating. “By changing the timing of food, it was possible to change the expression of not only genes in the gut or liver, but also thousands of genes in the brain,” says researcher Panda .
“By changing the timing of food, we were able to change the gene expression not just in the gut or in the liver, but also in thousands of genes in the brain,” said Panda.
By changing the timing of food, we were able to change the gene expression not just in the gut or in the liver, but also in thousands of genes in the brain,” said Panda.
The researchers also found that time-restricted eating aligned with circadian rhythms in several organs of the body.
“Every cell has a circadian rhythm, and we found that time-restricted eating synchronizes circadian rhythms with two main waves: one during fasting and the other just after eating. It allows the body to harmonize the different processes.
In summary, the results of this study found that TRF (a form of intermittent fasting) alters the relative levels of protein-coding gene expression and/or daily rhythms in >80% of mice in a tissue-specific manner.
However, a limitation of this study is that the transcriptome profiles were only from young male mice.
Therefore, more studies are still needed in the future to understand how TRF-dependent gene expression changes across tissues are affected by sex and age.
Intermittent Fasting Upregulates Sirt 3 Gene
A 2015 study published in the scientific journal Rejuvination Research found that subjects who fasted intermittently had upregulated levels of the SIRT3 gene in their bodies.
(The SIRT3 gene encodes a mitochondrial protein, a NAD+-dependent deacetylase, that is localized in mitochondria and is involved in a number of mitochondria-associated biological processes, such as energy metabolism, antioxidant defenses, and apoptosis, and has been implicated in a potentially protective “anti-aging” effect.)
To assess diet tolerance and explore the impact on biological mechanisms associated with aging and metabolism, researchers conducted a double-crossover, double-blind, randomized clinical trial that recruited 24 healthy individuals. Subjects were initiated on the IF dieting model.
The researchers assessed the expression of genes associated with aging and protective responses as well as markers of oxidative stress in the subjects.
In addition, satisfaction surveys were conducted and extensive adherence data were collected to assess the utility of the IF (intermittent) mode of fasting .
→Intermittent fasting upregulates SIRT genes
The researchers found that SIRT3 gene expression was upregulated in subjects who fasted intermittently.
(SIRT3 is primarily localized to mitochondria and is considered to be the major mitochondrial protein deacetylase in mitochondria. Studies have found that the SIRT3 gene, which helps protect against oxidative stress, is a longevity gene.