A person's entire immune system can be rejuvenated by fasting for as little as three days.

New Study on Fasting at USC
Modern professionals are also convinced of this ‘age-old’ theory. They feel that fasting will alleviate a host of ailments that plague us in our modern world. Scientists from the University of Southern California (USC) in Los Angeles have discovered a solution for people with weakened immune systems. They conducted a study, which is incidentally the first of a kind to demonstrate that a natural intervention can trigger regeneration of an organ or system through stem cells. The results of this study have been published in the journal Cell Stem Cell.The scientists think that fasting for a particular period shifts the stem cells of the immune system from a dormant state to an active state of self-renewal. They feel that fasting for as little as three days can actually regenerate the entire immune system. This is true not only for young adults but applies to the elderly as well. This discovery is a ‘significant and remarkable’ breakthrough in the scientific world.
In the past, fasting diets had been criticized by nutritionists for being unhealthy, but this new research shows otherwise. This study demonstrates that during the ‘starving’ or ‘fasting’ period, the body kick-starts stem cells into producing new white blood cells, which fight off infection. In other words, fasting "flips a regenerative switch" which prompts stem cells to create brand new white blood cells, leading to regeneration of the entire immune system.
The scientists feel that this research could be particularly noteworthy and beneficial for people suffering from damaged immune systems, such as cancer patients on chemotherapy. Apart from that, it could help the elderly patients, whose immune system becomes less effective as they age, making it harder for them to fight off even common disorders.
Valter Longo, Professor of Gerontology and the Biological Sciences at USC commented “We could not predict that prolonged fasting would have such a remarkable effect in promoting stem cell-based regeneration of the hematopoietic system. When you starve, the system tries to save energy, and one of the things it can do to save energy is to recycle a lot of the immune cells that are not needed, especially those that may be damaged. What we started noticing in both our human work and animal work is that the white blood cell count goes down with prolonged fasting. Then when you re-feed, the blood cells come back. So we started thinking, well, where does it come from?”
Fasting Cycles
Prolonged fasting forces the body to utilize glucose, fat and ketones stores in the body and at the same time it also breaks down a significant portion of white blood cells. Prof. Longo compares this effect to lightening a plane of excess cargo.This depletion of white blood cells induces changes that trigger stem cell-based regeneration of new immune system cells, which occurs during each fasting cycle. It has been observed that prolonged fasting also reduces the enzyme PKA, which is linked to ageing and a hormone, which reportedly increases cancer risk and tumor progression.
Meanwhile, more clinical studies are needed and there is no suggestion that people should try to get these same effects by prolonged fasting, which should only be done under medical supervision and under the guidance of a physician.
Health Benefits of Fasting
- Detoxification: In this process, the body neutralizes or gets rid of any kind of accumulated toxins in the various organs like the colon, liver, lungs, or skin. During the fasting process, the blood becomes filled with better levels of endorphins, which makes you more alert and provides a good mental health state.
- Weight loss: Fasting triggers the liver enzymes to break down fat and cholesterol into essential bile acids, which in turn stimulate the metabolism and convert the excess fat into heat. Fasting can prove to be the simplest and surest way to shed the excess fat with an acceptable amount of minimal side effects. However, it should always be done under the supervision of a medical practitioner.
- Promotes healing: Fasting also increases or promotes the healing process in the body. In a fasting state, the body focuses on other vital functions like metabolic activity and the immune system, rather than digestion, which is not necessary until a fed state is achieved. This leads to the overall production of healthier cells and tissues in the body.
- Feeling of Rejuvenation: In the fasting state, the body gets an opportunity to repair itself as a result of a slower metabolic rate, leads to improved mental state, improved blood circulation, and a feeling of rejuvenation. It leads to lower depression rates, stops insomnia, expands your creative thinking and transports the mind to a tranquil and joyful state. These effects in turn contribute to an extended life expectancy.