Updated: Dec 30, 2020
What is Intermittent Fasting??
Intermittent fasting or Time-Restricted Eating has been a widely spoken about health topic for quite some time.
You may often practice intermittent fasting without even realising!
It involves set time periods of when you rotate eating and fasting.
Most commonly, daily fasting-eating periods occur in 14:10, 16:8, 18:5 intervals, whereby fasting occurs for 14 hours and eating for 10 hours, etc.
Another method involves fasting for 24 hours once or twice a week.
Or, alternatively restricting your calorie intake on 2 days of the week. For those who track their calories or are aware of their calorie requirements, on the 2 days of restriction you would consume 25% of your normal daily intake.
The main aim in which majority of people begin intermittent fasting for is for weight loss due to fasting's impact on calorie restriction and reduction of late-night snacking.
However, there have been other extensive benefits on heart disease and cancer risk factors, in which intermittent fasting helps with. (1)
What does it help with?
As mentioned before, without having to consciously calorie restrict, weight loss is one of the most well-known benefits of intermittent fasting... with the assumption that you are not over-consuming food within your eating window!!
Physiologically speaking, weight loss occurs due to nocturnal hormonal increases and changes in insulin sensitivity allowing fat cells to be more accessible.
The increase of growth hormone increases muscle mass and breakdown of stored fat as well as uses the breakdown of fat for energy.
From the constant consumption of carbohydrates, insulin resistance occurs, causing weight gain and other associative conditions. However, in times of fasting insulin resistance decreases allowing the body to utilise carbohydrates efficiently.
A long side note - Consumption and breakdown of carbohydrates, results in glucose release into our blood stream. The hormone, insulin, transports the glucose and acts as a 'key' on the muscle and liver cells, where they stored as glycogen.
Here, carbohydrates are accessible as forms of energy. However, from long periods of overconsuming carbohydrates, the lock on our cell door becomes harder to open by insulin!
Once our cells resist insulin, glucose remain travelling in our blood and overtime causing nasty metabolic syndromes!!
Therefore, using periods of fasting allows our cells to become more sensitive to insulin and increases glucose utilisation, resulting in a healthy maintenance of blood sugar levels. (2)
Cellular repair and cellular autophagy, which is the clean-up of waste within your cells, has been found to improve during times of fasting.
The cleaning process through the removal of old proteins or dead cells, is essential for defence against oxidative stress and growth of cancer cells.
This combats dysfunctional autophagy, which has been found to enhance proliferation of cancer cells from damaged cells awaiting removal. (2)
Intermittent fasting has also been found to improve triglyceride and cholesterol levels, a marker of heart disease, more than calorie restriction.
Triglycerides are a form of fat, throughout fasting your source of energy changes from carbohydrates to fat, commonly known as being in ‘ketosis’.
During ketosis, the utilisation of circulating fat levels decreases which also affects reductions in potential atherosclerotic plaques.
Blood pressure has also been found to improve from reduction of high circulating cholesterol levels which usually place pressure on the arteries. (3)
Fasting has also been found to decrease markers of inflammation which can prevent chronic inflammation and associative conditions such as heart disease and cancer. (4)
Intermittent fasting has also been found to be protective against Alzheimer’s Disease.
As mentioned before, fasting enhances ketosis, which has a neuro-protective impact on ageing brain cells and boosts cognition. (5)
How about females?
Females have been commonly advised to fast for 12-14 hours or for 24 hours once a week. Studies have found evidence that fasting beyond these time frames causes female hormonal imbalances leading to overtime decreases in ovary size and absence of menstruation.
Metabolism has direct effects on hormone production whereby many nutrients are precursors to the synthesis of hormones.
Specifically, the female reproductive system is extremely sensitive to long periods of fasting. Therefore, disruption in hormonal production is evident.
However, previous studies showing these results have only been conducted on rodents undergoing intermittent fasting for 3-6 months. Advice to females of fasting for only 14 hours is precautionary to reduce any potential adverse effects. (1)
Don’t fret! 12-14 hours is more than sufficient to reap the benefits of intermittent fasting!
Before trying out intermittent fasting, make sure you address any potential medical conditions you have with a medical professional!