To eat or not to eat?
What if one of the most effective health interventions for longevity and modern chronic diseases, including obesity, cancer and dementia, was available to everyone, at any time? No prescription drugs involved! In recent years fasting has gained popularity among both the public and the scientific community for its many health benefits, yet, going without is not a new concept.
Before the advent of the agricultural revolution, around 10.000 BC, humans had to endure long stretches without food. Whilst this was involuntary, we also know fasting has been deliberately practiced since ancient times for physical, psychological, and religious reasons. It was observed that abstaining from eating has a restorative effect on mind and body. For instance, the loss of appetite during an illness naturally forces a fasting period during which energy and resources can be focused on recovery.
“Everyone has a doctor in him or her; we just have to help it in its work. The natural healing force within each one of us is the greatest force in getting well. Our food should be our medicine. Our medicine should be our food. But to eat when you are sick, is to feed your sickness.”
Hippocrates, Greek physician (460 BC – 377 BC)
By the 20th century fasting was well documented to have a broad spectrum of health benefits, offering improvements in irritable bowel syndrome, cardiovascular disease, arthritis, high blood pressure, diabetes, epilepsy and much more. However, soon after the arrival of prescription medication that managed the symptomatic manifestation of bad eating habits, fasting and dietary restriction fell out of favour. That said within the last few decades thanks to expanding scientific research and internet popularisation fasting has been rising to prominence once again and is being recognised and utilised as a viable therapeutic and health care strategy.
Today, our cupboards and fridges are well stocked all year-round. The opportunity and temptation to eat are constant, from food adverts, home deliveries, take aways, convenience stores and vending machines wherever we go. We are encouraged to eat 3 meals a day and snack in between. This nutrient excess results in digestive and cellular burden triggering a pro-inflammatory response, causing oxidative stress, and eventually organ damage.
What exactly is fasting?
We all naturally fast when we sleep and break-fast with the first meal of the day, therefore, fasting is simply not eating for a prolonged period of time. The most popular and well researched forms are time restricted feeding, intermittent fasting and extended fasts lasting up to 5 days. Depending on the duration of a fast different health benefits are derived at different stages. It is advised that fasts longer than 3 days are medically supervised. Beginners should take it slowly and build up to longer fasts if they wish to. Fasting of any duration, in particular, longer than 24 hours require preparation, and a refeeding consideration.
The ability to fast is a part of human biology which serves as a survival mechanism in times of low food availability.
What happens during a fast?
Fasting for a sufficient time (at least 16 to 24 hours) depletes glucose stores, lowers insulin levels, and triggers the release of stored fat, which the liver then converts into ketone bodies, a usable energy source. Ketones are not only cleaner energy substrates in comparison to glucose, but have powerful anti-inflammatory properties. Ketones are also known to modulate the activity of many molecules that influence health and aging.
Fasting puts the body in a catabolic state, which promotes cell repair but also cell death called autophagy (self-eating). Some level of autophagy is always occurring and is an essential process for eliminating damaged and dysfunctional cells that could otherwise clog up the system or become cancerous. Unfortunately, as we age oxidative stress accumulates therefore, cellular rejuvenation and autophagy become less efficient yet critical to overall health and longevity. Consistent fasting triggers an adaptive stress response that increases DNA repair, antioxidant capacity and protein quality control. Cells throughout the body, including brain cells, exhibit increased functionality and resilience to future damage. Therefore, promoting autophagy through fasting is an effective health management tool.
Summary of fasting benefits:
- Improved insulin sensitivity – cells are more responsive to insulin signalling allowing for better glucose clearance therefore protection from type 2 diabetes and inflammation.
- Ketone body production – alternative fuel to glucose with anti-inflammatory properties.
- Improved leptin sensitivity – prolonged excess energy and inflammation reduces cellular response to leptin a hormone that signals satiety.
- Ghrelin a hunger hormone reduces and so does the feeling of hunger.
- Growth hormone increases which helps preserve muscle mass, bone mass and collagen, growth hormone also offers neuroprotection.
- Weight loss where excess weight exists.
- Improved mood and alertness.
- Autophagy – ‘eating’ of old dysfunctional cells, which are replaced with new healthy ones.
- It saves time, money and offers flexibility around eating time.
What about feeling hungry?
Often, we eat not because we are truly hungry but because it is the ‘right’ time of the day or we are down, stressed, bored need distraction, or are in a social circumstance where we are expected to eat. The sensation of hunger comes and goes and lessens with time, and the same happens when you are fasting, for most people it never gets unbearable. Preparing for those moments when we are tempted to give in is key to a successful fast of any duration.
Is fasting for everyone?
Whilst fasting is beneficial for most it is not recommended for people with active eating disorders, people who are underweight, children, adolescents, athletes, and workers under great physical strain. Pregnant and breastfeeding women should not be fasting.