Fasting has long been a method of cleansing, a religious right of passage and championed as a way to better health since ancient times. Ramadan in Islam and regular fasting festivals in the Eastern Orthodox Church, Lent in the Christian calendar; the dogma of fasting and abstaining from food has been widely applied and advocated across history and cultures.. Indeed even the Paleolithic man would have periods of fasting due to necessity - ie there was no food around.
Dietary fasting has been promoted by various groups of people and philosophical beliefs for some time. Claimed benefits including reduced cholesterol, decreased heart and renal disease, improved digestive efficiency, increased insulin sensitivity and better immune function. Some critics claim that fasting only upsets circadian rhythms and destabiliises hormonal function. It's a heated debate, as I found, and depends very much on the information available. There are an incredible amount of variables that can influence the effects and benefits of fasting and these make each case for and against a very 'individual' choice.
So let's look at what fasting has traditionally promoted for the health of the body.
Increased Immune Function
By reducing free radical damage, regulating inflammatory conditions in the body and starving off cancer cell formation, Fasting is promoted as a key to healthy longevity. In nature, when animals get sick they stop eating and instead focus on resting. This is a primal instinct to reduce stress on their internal system so the body can fight off infection.
The digestive process diverts huge amounts of blood and is considered energy expensive. When we eat food the immune system gets activated to increase inflammatory conditions to ward off any unwanted microorganisms within the food. Two major cytokines Interleukin-6 and Tumor Necrosis Factor Alpha promote an inflammatory response in the body. Studies have shown that fasting reduces the release of these inflammatory mediators. Thus we can see a downgrading in inflammation by controlling our dietary intake, particularly appropriate in times of disease or illness.
By giving internal organs a chance to rest or 'take a holiday' they have the chance to cleanse themselves of debris and byproducts that occur from continual production and processing. Going without solid food can help to clear the intestines in particular, allowing them to flush the system and remove possible obstructions and deposits that are caused by continual ingestion. This is highly practised in yogic traditions with specific practices and postures advised to promote a flushing or shifting of the intestines whilst in the 'fasting' state.
Addressing Cholesterol -
Fasting helps moderate cholesterol levels (increasing HDL Cholesterol) - fasting promotes a periodic rise in HDL cholesterol (the good type) and the liver stops excreting cholesterol in general as it perceives it is needed for energy production. NB -Tests show that this effect stabilises after a 60hour period.+
Increases Growth Hormone Secretion in Males.
Fasting increases growth hormone secretion in males and reduces oxidative stress. Growth hormone is usually secreted during onset of deep sleep and is erratically and unpredictably released through different points of the day. Levels are also dependent on nutrient activity with insulin and fatty acids playing a role in the secretion of the hormone. Studies have shown a significant increase in GH secretion during a 5 day fast. There is a need for more controlled testing as GH secretion is influenced by various nutritional factors.
(Does not do the same in females - tests indicated a downgrade in hormonal activity with consequent issues in regulation of systems such as the reproductive cycle.) Interestingly in overweight subjects, the IGF-1 hormone (insulin based hormone) is actually downgraded^^ in production suggesting that insulin sensitivity is increased in fasting and insulin production is downgraded.
Maximises Metabolic Rate (pre 60hrs)
This is a slightly curly pro for intermittent fasting as the supposed increase in basal resting metabolic rate (significantly as a result in increased serum norepinephrine) is only present in already 'lean' test subjects. The claim that in the initial stages of fasting, the body changes its metabolism in preparation for the 'Starvation' mode. The body mass complex of test subjects would have an effect on test's already exisitng metabolic rates.
Activates Repair Mode
Intermittent Fasting (IF) has an effect on DNA sustainability via lengthening TELOMERE length in the
strand structure. Valter Long of University of Southern California goes further to explain that DNA repair genes are activated in times of IF which assists with cellular repair and restrict the formation of cancerous cells.
Meal composition plays a big part in absorption speed. Large protein rich meals before a period of fasting can mean that amino acids are still in the blood stream and being absorbed 16-28 hours after ingestion. This can healthily sustain a person to function normally and without impacting too greatly on the system. Catabolism would only exist after a prolonged period of fasting. which some sources claim can be up to 60hours. Various elements make this figure flexible, such as general health, body composition, eating habits, food ratio and fluid intake and activity levels and type.
"Mice under time Restricted Feeding (tRF) consume equivalent calories from High Fatty Diets (HFD) as those with unrestricted access yet are protected against obesity, hyperinsulinemia, hepatic steatosis, and inflammation and have improved motor coordination. The tRF regimen improved CREB, mTOR, and AMPK pathway function and oscillations of the circadian clock and their target genes' expression. These changes in catabolic and anabolic pathways altered liver metabolome and improved nutrient utilization and energy expenditure. We demonstrate in mice that tRF regimen is a nonpharmacological strategy against obesity and associated diseases."**
There is a lot of conjecture about the supposed benefits of fasting and how and when to do it. Critics of the system often cite associated gorging after fasting with a large issue, over-taxing the digestive system and stretching the ability of the body to process large amounts of food in one sitting. This seems reasonably obvious to me.
There is also the fact that fasting has become a way for peoples to lose weight. I re-iterate that this was NOT the reason that fasting was advocated in ancient and traditional societies. Yes there is a decrease in body weight in almost all tests that I have read but the composition of loss is not always of the most desired benefit. There is no point losing fluid and claiming to have lost bodyweight. You are only robbing your body of vital elements that are necessary for other bodily functions and in the end, you may actually overtax your systems negatively rather than promoting the healthy benefits such as improved renal function.
Also fasting is not a long term solution. People who do long term fasts are advocating the pursuit of a specific goal. Many Yoga practitioners fast for 10 days or more, to open spiritual pathways and attain higher levels of a spiritual practice. However, these people don't just decide to do a fast for 10days. They work towards this process and also employ a very specific physical practice to support and prepare them for such an event.
Buddhist Monks adopt fasting regularly throughout their practice as an 'empowering' practice to their commitment to their ideals. Rev Heng Sure Ph.D cites an excellent article that explains the doctrine of fasting for a buddhist, whilst eloquently advocating that this is a practice to be done under supervision and with consideration for all aspects of the individual.
Being informed and clear of the reasons for undertaking a fast are paramount to ensure why you should explore it as an option. Getting advice is best and no fast should be undertaken without first exploring the ramifications and considering what your lifestyle is at the time of the fast. It's an issue to be investigated before being undertaken.
When first undertaking this BLOG I was not prepared for the discussion at hand. Hence I will be continuing this topic over some time, as the information led me down a very well documented path with many differing opinions and subtopics within the discussion. Next week - Intermittent Fasting.
^^ V. D. Longo - Evidence for Programmed Aging
** Cell Metabolism" Volume 15, Issue 6 - M.Hatori
"Growth Hormone Secretion During Fasting" - Ho, Velduis, Furlanetto, Evans, Albertii and Thorner (Depts of Internal Medicine/Pharmacology, University of Virginia)
"Top Ten Fasting Myths Debunked" - Martin Berkhan, LeanGains.com Oct 2010
"Fasting and Yoga" - John McWhorter
"Why You Should Starve Yourself a Little Each Day" - George Dvorsky, io9.com
"IF Will Help Boost the Immune System" - David Jockers
"A Buddhist Perspective on Fasting" - Rev Heng Sure Ph.D www.paramita.typepad.com