Fasting explained
Fasting has traditionally been a religious practice, routinely undertaken at times throughout the year by many different religious groups.
It can have many health benefits to people. It has been linked to many positive health benefits including supporting the body’s ability to repair itself and weight loss.
Fasting also may even promote longevity (based on many animal models showing consistent results for calorie restriction and time restricted feeding).
Restricting food leads to energy depletion. Without sustenance, energy production is reduced. This signal is picked up by enzymes that then promote a process called autophagy.
Autophagy is the body’s process of recycling old or damaged parts of each cell to make new cellular apparatus. Other enzymes can be turned on in this process, important for repairing DNA.
Cells multiply all the time, so they need their DNA to remain the same, without mutations or damage in the blueprint for the next cell.
Fasting has been proven to help the body
A 5-week randomised controlled trial (1 ) in participants with a normal weight body mass index found that early time restricted eating improved insulin sensitivity more than mid-day time restricted eating.
Intermittent fasting (2) can reduce body weight, blood pressure, insulin resistance and oxidative stress.
Various forms of intermittent fasting (3), with and without exercise, have shown to reduce fat mass. When this is combined with resistance training, there has also been minimal loss of lean mass observed. Therefore, it may be an effective way of improving body composition.
Fasting has been scientifically proven to help the body
Fasting and weight loss
Fasting can lead to calorie restriction, which in turn can result in some weight loss. However, there are several reported ways in which fasting may benefit weight loss or improved body composition.
In the absence of sugar, the body turns to fat for fuelling the body. Fasting can be combined with exercise and this enhances the fat burning process.
Some evidence also suggests that restricting energy intake too early in the day can regulate the body’s circadian rhythm (its internal day and night clock) and subsequently improve metabolism of macronutrients (carbs, fats and proteins).
In doing this, appetite can be better regulated throughout the rest of the day. It is why many people report (4) being less hungry on days when they fast.
Genetic factors do contribute to these mechanisms, accounting for some people to benefit from these processes more than others.
Supporting your wellness while fasting
Staying hydrated during times of fasting will help maintain optimal cellular function, alongside maintaining the blood volume.
This may help minimise the chance of experiencing adverse events with fasting.
Finally, practice gratitude for your body when fasting. How amazing is it that your body is so incredibly adapted to heal and repair, if you give it a little break and time.
It is a wonderfully complex biological machine that is the outcome from millennia of evolutionary pressures, to ensure it can survive and adapt.
And some gratitude for the science. New science is helping us to support our bodies in ways previously thought to be associated malnutrition, leading to poor health, such as fasting.
Staying hydrated during times of fasting is essential.
The ideal length of fast time for maximum benefits
This is different for everyone and if you are not in the group of people where fasting is not recommended (see below) then personal preference, daily schedule and goals will need to be considered, to allow for a healthy and appropriate fast.
These can be determined with your doctor or medical professional.
Different methods include:
Reducing eating window each day. Increasing the number of hours in a fasted state can help to activate the enzymes for autophagy and repair. Eating in window of 4,6 or 8 hours is a popular method, allowing for most of the day to be in a fasted state. This typically will involve skipping a meal like breakfast or the evening meal. Doing this throughout the week or intermittently on certain days can help to increase the body’s time in fasted state. This is called time restricted feeding. These can be described as 16:8 or 20:4, showing the number of hours fasting compared to the number of hours eating.
OMAD – one meal a day – is another popular method. This one meal must be heavily nutritious if this is practised often.
Fasting for a full day or multiple days at intervals throughout the week, month or year is another way to increase the time that the body is in the fasting state. This a more extreme method of fasting and may involve a 24, 48 or 72 hours fast, a few times per year.
Some experts will suggest during fasting that non-calorie or non-macronutrient based drinks, such as black tea or black coffee can be consumed during the fasting period.
Other experts suggest only water should be consumed during the period. Science has not quite revealed the best method here, however, the benefits can be noted by both methods.
A way of monitoring if there is a positive effect or not is to different biomarkers with your doctor or medical professional, assessing things like blood sugar control, blood pressure, heart rate, liver function and cholesterol. Improvements in these will help to inform if fasting is helpful to your health or if the method of fasting is being effective.
Eating when you come out of a fast
Refeeding after a fast is really important. Ensuring that the body has access to all amino acids will be essential.
The best way to do this is to make sure there is at least 0.5grams of animal protein per 2Kg of weight with your first meal.
If you do not consume animal proteins, then ensure that you get this level of protein from plant sources and consider supplementing with the key amino acids found in animals, such as methionine and leucine, to help preserve muscle tissue and ensure the body’s metabolism (its many reactions) can return to normal.
The other important element to consider when fasting, and is often the reason people may not feel the benefits, is to avoid malnutrition.
Eating in a smaller window or after a prolonged time of not eating, increases the risk of nutritional deficiencies.
When refeeding occurs, it is vital to ensure that your body gets all of the nutrients it needs, including vitamins, minerals, proteins and fats.
For example, the activated form of vitamin B3, called nicotinamide adenine dinucleotide (NAD) is consumed by enzymes (sirtuins) involved in DNA repair during times of fasting. The body needs NAD as fuel for hundreds of reactions, so ensuring levels are replaced are essential to replenish stores to ensure the body can run optimally and that stores are preserved for the next fast.
If you wanted to support your body with NAD or vitamin B3 supplementation, REVIV offer both NAD+* and vitamin B3 as IV drip therapy (Megaboost) and IM booster shot (Super B).
Breaking your fast needs to be done mindfully.
Fasting can put pressure on your vital organs
If fasting is not done properly and energy production remains low, then the cells of the organs do not get the energy they need to function properly.
Similarly if the food quality when eating does occur is low or deficient in nutrition, like many ultra-processed foods, then the organs can be starved of essential vitamins and minerals, effecting their health and function.
There are people who shouldn’t fast
Fasting is not for everyone. Women who are pregnant, women currently nursing a child, children, people healing from acute injury and people with metabolic disorders should avoid fasting, if possible.
Pregnancy and lactation are extremely energy intensive, and fasting can affect health in these conditions. Fasting in childhood can lead to impaired growth in children.
People that have genetic mutations of their energy producing metabolic pathways can be more at risk of hurting their health when it comes to fasting.
There are 1400 known mutations of these energy pathways and it is thought that 2 or more mutations of these pathways could be enough to cause disruption to normal function, hurting the cells.
You should stop fasting if you experience:
- Dizziness or light headedness
- Headaches
- Severe hunger sensation
- Fatigue
- Blurred vision
- Fainting
These things can be helped by rehydrating and refeeding the body with good quality foods.
Fasting and mental health
This isn’t a hugely studied area as it is harder to measure but this (5) meta-analysis showed that intermittent fasting did not negatively impact mental disorders in the general population.
In fact, it showed a positive influence on diminishing depression scores, but it did not modify anxiety or mood.
A total of 14 studies involving 562 individuals were included, of which eight were random control trials. Intermittent fasting showed a moderate and positive effect on depression scores when compared to control groups.
If you’d like to know more about how REVIV could support your fasting or you have any other questions, please do not hesitate to contact your local clinic for more information.
*NAD+ is available in some clinics and has not yet launched into the UK
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