Intermittent fasting is a scheduled eating plan in which food intake is restricted to a certain length of time. The most common way of doing it is to restrict eating to a window of about six to eight hours. This can be done daily, every other day or even weekly.
How Intermittent Fasting Works
When you are fasting intermittently, your body functions differently during the ‘feasting’ stage than it does during the ‘fasting’ stage. The food you eat during the feasting period is digested and the energy it contains is extracted into the blood stream. As it is in the blood, and thus immediately available, this is the energy your body will burn.
During the fasting period however, the opposite happens. As you haven’t eaten for a long time, there is no surplus energy in your blood stream just waiting to be used. So, when energy is needed, your body has to take it from the next available source – it’s fat stores.
Typically, the fast times are between sixteen and eighteen hours – some people do it for longer periods such as thirty six hours and even several days. We don’t advise this however, as it is taking the concept to extremes that really aren’t necessary. The way we do recommend is to skip breakfast, eat your lunch around midday and your dinner by 6.00 pm. Then eat nothing until lunch the following day and so on. By doing so, you’ll be eating within a 6 hour window and fasting for 18 hours.
If done correctly, intermittent fasting offers a range of benefits that include the following:
The theory of intermittent fasting as an aid to weight loss is based on the fact that the body stores sugar as glycogen in the liver but only enough for six to eight hours. So assuming nothing else is eaten during this period, i.e. the glycogen store is not topped up, after six to eight hours it will all have been used up. This compels the body to switch to the next available fuel – its stores of fat. Essentially, the process replicates (to a degree) what our ancestors were often exposed to in terms of food availability.
Intermittent fasting compels you to eat less frequently. Unless you eat more when you do eat in order to compensate, your calorie intake will be less and you will lose weight – it’s as simple as that!
Intermittent fasting also induces changes in the way certain hormones act. For example, human growth hormone (HGH). Intermittent fasting causes the levels of these hormones to rise, one effect of which is to trigger the burning of fat. At the same time, it also helps build muscle. Another effect of these hormonal changes is that the body’s metabolic rate increases by up to 15 percent. This, in turn, leads to even more calories being burned and so more weight being lost.
An interesting aspect of intermittent fasting as a means of losing weight is that a lot of the fat burned is from around the waist and hips – traditionally the most difficult parts of the body from which to lose fat.
Reduced Risk of Insulin Resistance
Insulin is a hormone produced by the pancreas and its purpose is to enable the body’s cells to absorb glucose. When the human body becomes insulin resistant, its cells cannot absorb glucose as they should and so to compensate, it produces more and more insulin. Eventually, the pancreas can no longer produce enough of the hormone for the body’s needs. The result of this is a sharp rise in blood sugar level.
Causes of insulin resistance include:
- chronic stress
- high doses of steroids
- a sedentary lifestyle
- a diet high in carbohydrates
- being overweight or obese
Ensuring none of these apply to you will eliminate, or at least considerably reduce, the risk of insulin resistance. Another method is intermittent fasting. Recent studies have demonstrated that it reduces both blood sugar levels and insulin by a considerable degree.
Reduced Effects of Aging on the Brain
Research shows that intermittent fasting can have a significant effect on the human brain in a couple ways:
The first is that intermittent fasting causes the body to stop using glucose as an energy source and instead use fat. When it does this, the fat releases substances known as ketones. These are used by the body, the brain in particular, as an alternative fuel source. As ketones are a more efficient fuel than glucose, the brain receives a significant boost of energy.
The second is that ketones increase the number of mitochondria (minute organs that generate energy) in brain cells. This happens particularly in the hippocampus, a part of the brain that handles learning and memory. Cells in the hippocampus are known to degenerate when subjected to age-related brain diseases such as Alzheimer’s and Parkinson’s disease. This can lead to cognitive impairment, loss of memory and more. Thanks to the increased amount of energy provided by the ketones, however, brain cells that would otherwise die are able to survive.
The takeaway here is that intermittent fasting is associated with improved motor coordination, learning response and a decrease in oxidative stress (oxidative stress is what we often consider normal age-related change). So intermittent fasting improves healthy aging of the brain and decreases the cognitive decline that is generally considered a normal part of the aging process.
Regeneration of the Immune System
Humans have a type of cell known as a stem cell that have the ability to mutate into different types of cell. These stem cells stay dormant until they are activated by disease or an injury to body tissue. When they are activated, they can generate a range of cell types from the originating organ, or even regenerate the entire original organ. In other words, stem cells provide the body with a way of repairing and renewing itself.
A related body function is known as mitophagy, the literal meaning of which is ‘self eating’. This is a process that enables the body to clean and detoxify itself by, quite literally, eating cells that are no longer needed or are damaged. The process is also thought to have a role in controlling the body’s immunity system and inflammation. However, mitophagy doesn’t just happen – it has to be kick-started. The way to do it is by subjecting the body to an unusually high level of stress. There are three methods of achieving this:
- Exercise – strenuous workouts damage your muscles by causing microscopic tears that the body then has to heal. This makes the muscles stronger than before, more resistant to further damage, and also builds new tissue. The more intense the exercise, the greater the benefit
- Eating a ketogenic diet. This forces the body to burn fat to fuel itself and enables people to lose body fat while, at the same time, retaining muscle
- Intermittent fasting. Although it wasn’t always so, this is now an unnatural thing for us to do and so our bodies find it a stressful experience. When the body is in a ‘fed’ state, mitophagy is low. However, when in a ‘fasted’ state, the opposite applies – insulin levels drop and mitophagy increases
Reduced Risk of Cardiovascular Disease
Triglycerides are a type of fat that is used to store excess energy from our diet. A high level of it is associated with cardiovascular disease and insulin resistance. Intermittent fasting is known to reduce the level of this type of fat significantly.
Reduced Levels of Inflammation
Inflammation is the immune system’s response to damage or danger. This can be bacteria infecting a wound or a splinter in your finger, for example. It is not always helpful to the body though – with some types of disease the immune system actually attacks itself by mistake. Examples of this include psoriasis, Crohn’s disease and rheumatoid arthritis. These are all chronic inflammatory diseases that can last for years, or even a lifetime, in varying degrees of severity.
A substance called Leukotriene B4 plays an important role in a number of cellular processes involved in inflammation. It is known that a diet high in fish oil decreases the production of Leukotriene B4. With this fact in mind, recent studies have been done to see if a reduction in calorie intake would also have a beneficial effect. The results have all shown that fasting, both intermittent and long-term, causes a decrease in the production of Leukotriene B4 and thus has an anti-inflammatory effect.
Do’s and Don’ts of Intermittent Fasting
Intermittent fasting is straightforward enough. That said, there are a few things you need to be aware of before you start:
DON’T do it if you are pregnant, diabetic, have any underlying medical problems or are taking prescription drugs.
DO listen to your body. If you feel abnormal in any way, don’t be a hero – stop immediately. In particular, heart palpitations, dizziness and weakness must not be ignored.
DON’T do strenuous exercise while fasting. Light stuff is fine but it’s best to avoid things like high-intensity cardiovascular exercise, especially if you’re not used to it.
DO ensure you are drinking enough water. A large proportion of our water intake is from the foods we eat, so you will need to compensate by drinking more than you normally do.
DON’T fast intermittently if your usual diet comprises a lot of processed foods. Addressing the quality of your diet is crucial before you start fasting. Take a couple of weeks to slowly cut back on the refined carbohydrates, sugar and grains. Foods you should eat are those rich in natural carbohydrates, protein, and healthy fats – eggs, cheese, butter, olive oil, coconut oil, avocados, nuts, etc.
DO work to a schedule by only eating in the same window. Working to a routine makes it easier to stick with.
DON’T give up! Half of the fasting period is when you’re asleep. That just leaves eight hours or so. Drink water and tea whenever you start to waiver.
Some lucky people are able to lose weight easily. Most, however, find it anything but easy. You think you are doing everything that you should be but the weight stubbornly refuses to disappear. Intermittent fasting may be the answer. It also offers a range of other benefits.
However, do make sure your body is up to to it before you start. If in any doubt, consult a healthcare professional.