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Intermittent fasting – all the knowhow
Intermittent fasting is a method of time-limited eating (usually 16 hours of fasting and 8 hours of eating) that has gained popularity in recent years. The method shows promise as a potential new approach to weight loss as well as reducing inflammation and has many potential long-term health benefits. In this blog we will summarise as much complicated – but relevant – literature as possible to create more clarity surrounding fasting.
What is intermittent fasting?
The term intermittent fasting refers to reduced calorie intake on an intermittent basis. This can vary from a few hours to a full 24-hour period. It can be done for religious reasons, such as the Ramadan or Yom Kippur, or for health reasons such as weight loss. Intermittent fasting is used in many ways to describe different types of calorie restriction.
- Some authors use it when a patient withholds calorie intake for several consecutive hours during the day (often 16 hours with all energy intake during the other 8 hours of the day).
- Others a full day once or twice a week and others three or four days a week.
- Some protocols allow protein but not carbohydrates and still call it intermittent fasting.
- Others allow carbohydrates or macro/micronutrients to a limit that still promotes ketosis and while it is simply a low-calorie diet, it has been labeled a fasting diet due to the popularity of fasting.
- In all cases, no caloric fluid intake is allowed (which is one of the main differences compared to religious fasting) and therefore significantly reduces the risk of dehydration and hypotension.
How to approach intermittent fasting
If you’re reading this blog, you’re probably considering fasting. As mentioned before, there is not one guideline for intermittent fasting, but there are different ideas about it. The two most practical are listed below.
You can take a daily approach, limiting daily eating to a period of six to eight hours a day. For example, you can choose to fast for 16/8: eat eight hours and fast for 16 hours. Research shows that most people find it easy to maintain this pattern over the long term.
Alternative fasting day
Another well-known approach is the alternate fasting day, which can consist of a 24-hour fast followed by a 24-hour eating period that can be done several times a week, such as a 5:2 strategy when 2 fast days are mixed in 5 non-fasting days. fasting days. The 5:2 strategy is also sometimes used for the strategy of eating normally for 5 days and eating only 1 meal of 500-600 calories two days a week.
Side note to fasting
- Longer periods without food, such as fasting 24, 36, 48 and 72 hours, are not necessarily better for you and can even be dangerous. Going without food for too long can encourage your body to store more fat in response to starvation.
- Research shows that it can take two to four weeks for the body to get used to intermittent fasting. You may feel hungry or cranky as you get used to the new routine. But it is noted, subjects who get through the habituation periods tend to stick to the plan because they notice that they feel better.
Health Benefits intermittent fasting
Between 2013 and 2017, many studies have been conducted into the health benefits of intermittent fasting. The main reason for this is the rapidly growing number of obese patients, who are often subjected to a calorie-restricted diet. This diet does not always appear to be effective because of the chance that the patient can sustain it for a longer period is relatively small. In addition, bariatric surgery has a 0.25% risk of death and a 13% risk of serious postoperative complications, according to the Swedish Obese Subjects study. This functions as a compelling example of intermittent fasting its rising popularity. But not just for obese subjects, also for people without obesity as later shown in this blog.
It helps in weight loss
Many studies on intermittent fasting have been done on rodents. Losing weight is an exception and therefore the most relevant. Besides the fact that when you fast, you often take in fewer calories than when you eat a large meal 3 times a day, there are also other factors that ensure that you will eventually lose weight.
A 2019 study involving healthy young people (mean age 29 and mean BMI 20) analysed various metabolic markers via fasting blood draw. These metabolic markers are substances that ultimately influence the metabolism. Results from this study were that short-term fasting (58 hours) induces a metabolically active state much more than previously realised. This means that fasting turned out to have a much greater effect on speeding up the metabolism than initially thought, and a more active metabolism ultimately results in faster calorie and fat burning.
More concrete evidence came from a review of several scientific articles from 2014. It had been concluded that intermittent fasting could cause a weight loss of 3-8%, these results were achieved in a time frame of 3-24 weeks. In the same study, the participants’ waist circumference was measured. The participants lost 4-7% of their waist circumference in a period between 6-24 weeks. That the waist circumference is reduced indicates the loss of visceral fat. Visceral fat is the harmful fat in the abdominal cavity and around the organs, fat in this place can cause a lot of damage to the organs in the long term.
Reduced risk of cardiovascular disease
Clinically, lowering LDL is the common and effective method of preventing cardiovascular disease. Statins can powerfully lower total and LDL cholesterol levels by decreasing cholesterol synthesis in the liver. Although statins have been recommended as first-line therapy for the treatment of cardiovascular disease, their effect is very limited. In addition, an adverse effects on cognition, liver and muscle by statins have been observed.
Ultimately, the chronic inflammation that develops in cardiovascular disease is the most important risk factor. Therefore, an anti-inflammatory method may improve the outcome of patients on LDL-lowering therapy. A study was published in September 2021 that looked at this inflammation, in mice. The control group received a meal 3 times a day, the other group received a meal 3 times a day for 3 days and a full fast for 1 day. The study lasted 7 or 14 weeks after which the following conclusions could be drawn:
- Intermittent fasting inhibits the progression of cardiovascular disease. It was found that aortic injury was significantly reduced by 24-35% after 7-14 weeks in the mice on an intermittent fasting diet.
- Intermittent fasting lowers cholesterol by inhibiting cholesterol synthesis in the liver. When substances such as Serum TC and LDL-C with high levels are present in the body, they give a very increased risk of cardiovascular disease. In this study, it was found that both TC and LDL-C levels were significantly reduced in the intermittent fasting diet groups. In addition, a pale liver color was found in the control group of mice, which indicates an accumulation of fat particles in the liver.
Reduced risk of type 2 diabetes
With type 2 diabetes, the body no longer responds well to insulin. That is the hormone that regulates blood sugar. The insulin is invisible, as it were, and cannot do its job. As a result, too much sugar remains in your blood. At first the body makes extra insulin, but over time this is less and less successful.
In 2014, a first human study was conducted to see whether intermittent fasting works the same or better in type 2 diabetes patients, compared to the current standard calorie-restricted diet. They summarised the results as follows: “Overall, these preliminary findings show promise for the use of intermittent fasting as an alternative to calorie restriction for weight loss and type 2 diabetes risk reduction in overweight and obese populations, but more research is needed before solid conclusions can be drawn”.
In addition, there were two small studies in 2017 and 2018 that looked at whether intermittent fasting can reduce insulin injections for people with type 2 diabetes. In both studies, waist circumference and weight decreased. All patients who participated were able to discontinue insulin treatment. Which means that intermittent fasting can provide a better decrease of blood glucose in comparison to drugs or extra insulin.
Intermittent fasting can help prevent cancer
Cancer, being one of the leading causes of death worldwide, is striking more and more families. Although anticancer therapy has been greatly improved, it still has limited efficacy for tumor eradication and is highly toxic to healthy cells. New therapeutic strategies to improve chemotherapy, radiotherapy and targeted therapy are thus an important target in cancer research. Macroautophagy is a conserved lysosomal degradation pathway for the intracellular recycling of macromolecules and the clearance of damaged organelles and misfiled proteins to ensure cellular homeostasis. Dysfunctional macroautophagy is a contributor to plentiful diseases, including cancer. Macroautophagy can suppress or promote tumors depending on the stage of development and tumor type and modulating macroautophagy for cancer treatment is an interesting therapeutic approach that is currently under intense investigation. In this study, researchers explain that dietary restriction is a promising protocol to modulate macroautophagy and enhance the efficacy of anticancer therapies while protecting normal cells.
A 2020 review article reviewed 307 reports regarding the effect of intermittent fasting on cancer development. Most studies concluded that intermittent fasting had a positive effect on tumorigenesis, either by slowing cancer incidence by reducing tissue damage and inflammation, or by reducing the risk of certain types of cancer. Despite the large number of studies included, more clinical experiments are desperately needed.
What it comes down to
Intermittent fasting is a very popular weight loss method, but the benefits extend beyond that. It can also help you live healthier and longer lives, according to animal and human studies.
There are many ways to practice intermittent fasting. Some methods include fasting for certain hours each day. Other methods require you fasting only on certain days of the week. If you’re interested in starting intermittent fasting, consider talking to a doctor or nutritionist. They know how to help you determine if it is safe for you.