Fasting is abstaining from food for a prolonged period of time. It allows our body to take some rest from digestion and enables it to allocate some energy in improving the functions of organs like liver, kidney, skin. This enables the organs to perform better.
Fasting started as a religious practice. It was a complete refraining of food intake for a prolonged duration of time. It was practiced as intentionally denying the body what it needed, to gain a response from the spirit.
As times passed, renowned physicians like Hippocrates started believing that fasting could be used as a therapy to enable the body to heal itself. Fasting if done in a proper way benefits us in many ways. There are many different methods of fasting. Intermittent fasting (IF) is one of them and now very much in trend.
What is Intermittent Fasting?
Intermittent fasting is a pattern of eating where you fast for a certain duration of time followed by a non-fasting period. It is a cycle between fasting and feasting. While severe calorie restriction is never advised, intermittent fasting is advisable. It is sustainable and has shown to be beneficial on several health parameters. There are different methods of achieving intermittent fasting.
1. The 16/8 method also known as Leangains diet
In this method, you fast for 14-16 hours and restrict your daily eating time to 8-10 hours. Within this window, you can have as much as 3 meals or more.
2. The 5/2 diet
In this method, you eat normally for 5 days a week and restrict your calorie intake to 500-600 calories for the rest of the 2 days.
3. Eat-Stop-Eat also is known as Periodic fasting
Eat-Stop-Eat is intermittent fasting, in which you fast either once or twice in a week.
4. Alternate day fasting
As the name infers, you undergo an alternate day of fasting. The idea is to fast one whole day and feast the next day and continue the pattern.
5. The Warrior Diet
A warrior diet is a form of intermittent diet that mimics the eating pattern of the ancient warriors, who ate very little during the day and feasted at night. It is a type of intermittent fasting with 20 hours of under-eating followed by a 4 hour of overeating.
Amongst all of them, which method works for you the best depends upon your personal preferences and your ability to refrain food for that much duration.
13 Evidence-Based Health Benefits Of Intermittent Fasting
Intermittent fasting as a weight loss approach was popularized in 2012 by a journalist Dr. Michael Mosley’s TV documentary ‘Eat, Fast, Live longer’. This was followed by journalist Kate Harrison’s book ‘The 5:2 Diet’ which was based on her own experience. Intermittent fasting again came into the forefront in 2016 by Dr. Jason Fung’s bestseller book ‘The Obesity Code’. It generated a steady positive response as its effectiveness spread out.
Many researchers have conducted studies to observe the effects of this fasting regimen. Here are 14 scientifically proven health benefits of intermittent fasting, when done correctly.
1. Promotes Weight loss
Restriction of calorie intake is an effective way to lose weight in people who are overweight and obese. The food that we eat is broken down in our stomach and intestine by the enzymes in our body and end up as molecules in the blood. Carbohydrates, particularly sugar breaks down into glucose which the cells use for energy. The unused part is stored in our fat cells as fat.
Insulin is the hormone produced by the pancreas, that manages our blood sugar level. It is responsible to allow the entry of this sugar in the cell. The eating pattern that is associated with intermittent fasting reduces the level of insulin. This decreased level of insulin may increase the burning of fat as fuel for energy because of the lack of sugar in the cell promoting weight loss.
Intermittent fasting also increases the level of norepinephrine, a hormone that boosts the metabolism of our body. This, in turn, increases the calorie-burning capacity of our body which ultimately aids weight loss.
Studies have shown that intermittent fasting helps our body retain muscle mass in a better way than a normal calorie-restricted diet. In 3-12 weeks, Intermittent Fasting may reduce the weight of the body by 8 percent and decrease body fat by up to 16 percent.
The keto diet which includes a very high intake of fat and restricted intake of carbohydrate is designed to force the body into a metabolic state called ketosis. In this state, as the body gets deprived of glucose, it is forced to break fat for energy.
That results in a considerable weight loss. Combining a keto diet with intermittent fasting may help your body enter ketosis faster and thus maximize the result.
Summary: Intermittent fasting restricts the overall calorie intake in the body. This is an effective tool to reduce weight. It also boosts metabolism resulting in the breakdown of fat cells.
2. Reduces Blood Pressure
Hypertension is a condition in which the pressure of the circulating blood against the blood vessel is very high. Two forms of pressure are measured. The systolic blood pressure and diastolic blood pressure.
The systolic blood pressure is the amount of pressure in our arteries when the heart muscle contracts. The diastolic pressure refers to the pressure of the blood when our heart muscle is between beats. The normal blood pressure reading is 120/80.
When the blood pressure exceeds 140/90, it is considered hypertension.
In the United States alone, this problem affects 86 million adults. It is a risk factor for cardiovascular disease, stroke, and chronic kidney disease. Intermittent fasting has a beneficial effect on lowering the systolic blood pressure.
Some studies also found a positive impact of Intermittent fasting on the diastolic pressure. More studies need to be done in this field. This has been documented in animal studies, and later it was confirmed on humans.
Studies conducted at the University at Buffalo in the United States in male rats confirmed the beneficial effect. Studies on the effectiveness of the diet also have been confirmed in humans conducted at Buchinger Wilhelmi clinic in Germany.
Summary: Intermittent fasting reduces insulin secretion and improves weight loss. As both of them are responsible for high blood pressure, reduction lowers the systolic blood pressure.
3. Reduces Inflammation and Oxidative Stress
Oxidative stress is an imbalance between the antioxidants and free radicals in our bodies which leads to cells and tissue damage. This is a natural process and plays an important role in the aging process.
A range of chronic conditions develops due to long term oxidative stress. They include diabetes, cardiovascular diseases, and cancer.
In oxidative stress, unstable molecules which are the free radicals react to the other molecules like DNA and protein and damage them. Studies have shown that intermittent fasting may enhance the body’s ability to resist this oxidative stress hence the ability to reduce inflammation.
Summary: Intermittent fasting lowers inflammation by reducing the oxidative stress in the cells.
4. May Lower Cholesterol Levels
Intermittent fasting has shown great benefits in lowering the overall cholesterol level by reducing Low-Density Lipoprotein (LDL) level in the body.
After eating a meal, the concentration of glucose in the body increases and then within a few hours, it returns to the state it was before the meal. The concentration of ketones is low because glycogen stores in the liver are not depleted. During the use of the IF diet, which consists of introducing fasting periods, there are marked metabolic changes in the body.
For example, when using a diet during which all food during the day is consumed in a 6-hour nutritional window, the glucose level is elevated during and about 6 hours after a meal but remains low for the remaining 16 hours until the next day. During this 6–8 hours in an 18-hour fasting window, ketones remain increased. The human body is naturally adapted to such periods of fasting and in the moment of starving, adaptation mechanisms are used to obtain energy.
During fasting, when glucose is exhausted, the body begins to utilize these ketones that arise as a result of fatty acid transformations. Fatty acids and ketones become the main source of energy for cells. This transition is called intermittent metabolic switching or glucose-ketone switchover. Inverse switching, which is the ketone-glucose, occurs after the interruption of fasting and meal intake.
Such biochemical changes are accompanied by cellular and molecular adaptations of neuronal networks in the brain. The result is an improvement in their functionality and resistance to stress, injuries, and diseases. The above biochemical transformations of lipids, along with following the IF diet, result in weight loss and changes in lipid parameters.
An 8-week alternate day fasting study was done on 26 obese participants. There was a considerable reduction of LDL cholesterol in all of them. Another study that followed a 22-day alternate day fasting regimen showed an increase in HDL, LDL, and triglyceride level but an 8-week time-restricted study showed improved HDL/LDL ratio. An analysis by the American Heart Association of different short term studies showed a consistent decrease in LDL levels from 7 percent to 32 percent.
Summary: Intermittent fasting reduces the insulin concentration in the blood thereby switching to fat burning as an energy source. Intermittent fasting may reduce the Low-Density Lipoprotein in the body to quite an extent and shows an improved HDL/LDL ratio.
5. Fasting Boosts Stem Cells’ Regenerative Capacity
As people grow old, their intestinal cells start to lose their regenerative ability. These stem cells are the source of all the new intestinal cells. So the decline can make it difficult to recover from gastrointestinal infections or other conditions that are related to the intestine.
According to a new study from MIT biologists, it has been confirmed that this age-related loss of stem cell function can be reversed by fasting. The researchers found that fasting improves stem cells’ ability to regenerate.
The cells begin breaking down fatty acids instead of glucose for their fuel requirement. This is a very important change that boosts the regeneration of the cells. The researchers found that the boost was with a molecule that activates the same metabolic switch.
Such an intervention can potentially help people who are old recovering from infections or cancer patients undergoing chemotherapy.
Summary: Intermittent fasting has shown to reverse the age-related loss of stem cell function and boost its capability to regenerate.
6. May Boost Brain Function
Intermittent fasting comprises a lengthy duration of fasting. Going without food for such a long period increases the brain’s natural growth factors, which are responsible for supporting the survival and growth of neurons.
As fasting leads to metabolic switching between glucose and ketones, it impacts multiple signaling pathways that promote neuroplasticity and acts as protection against the brain to injury and disease.
Summary: Intermittent fasting increases the brain’s natural growth factors which are responsible for supporting and growth of neurons thereby boosting brain function.
7. May Reduce Risk of Stroke
There are numerous risk factors for stroke. They range from obesity to unhealthy lifestyles like smoking. High blood pressure, diabetes and heart diseases are the biggest contenders.
Studies have shown a positive link between fasting and reduction of the risk factors that lead to stroke. Intermittent starving has been shown to reduce the blood sugar level and blood triglyceride level.
Subjects undertaking intermittent fasting clear up their blood triglyceride level better and quicker than the placebo group. Since IF also reduces the systolic blood pressure by 9 percent and it is more efficient in reducing pressure on arteries, which may reduce the likelihood of heart attacks and strokes.
In addition to reducing the risk of stroke, researchers have found that calorie restriction supports neurogenesis, the creation of new neurons and neuronal connections, after a stroke.
Summary: Diabetes, high cholesterol, high blood triglyceride, high blood pressure are some of the risk factors of stroke. Intermittent fasting has a positive effect on all of them diminishes the chances of stroke.
8. Increases Cell Turnover (Autophagy)
During intermittent fasting, the cells in our body initiate a process called autophagy. It is a way of removing waste from our body.
It involves the breaking down of the cells and metabolizing the broken and dysfunctional protein that accumulates in the cell over a period of time. This cellular process protects us from several diseases which include cancer and Alzheimer’s disease.
Summary: By initiating the process of autophagy, Intermittent fasting helps remove waste from the body and protects us from several diseases.
9. Lowers Risk of Cardiovascular Diseases
According to the World Health Organization, cardiovascular diseases are a serious problem in this modern era. There are nearly 17.9 million deaths every year due to cardiovascular diseases. They affect people who are 45 years or more of age.
The contributory factors that are responsible for the development of this disease are both modifiable and unmodifiable. Age, gender and genetic factors are beyond our control but smoking, obesity, hypertension, diabetes, a disorder of lipid metabolism and poor diet are the modifiable factors that can be controlled. The coexistence of any two or more of these factors increases the likelihood of cardiovascular diseases.
With the problem of obesity growing day by day, diet changes are an important factor that can be modified. It is recommended to eat a large number of vegetables, fruits, fish and whole-grain bread.
Currently, intermittent fasting is growing in popularity and has been more effective in comparison to the traditional method of calorie restriction. Intermittent fasting has been proved to be helpful in people suffering from obesity and diabetes and regulates the blood pressure, thereby restricting the progression to cardiovascular diseases.
In intermittent fasting, fatty acids and ketones become the main energy fuel and the body switches its energy source from glucose to ketones. By affecting the biochemical transformation of lipids, the body mass decreases and the lipid profile parameters like cholesterol, triglyceride, and LDL cholesterol concentration reduces.
Intermittent fasting hinders the development of atherosclerotic plaque. It reduces the concentration of inflammatory markers.
Summary: Fasting regularly may decrease LDL cholesterol or bad cholesterol. It also improves the way the body metabolizes sugar. As this reduces the risk of gaining weight and developing diabetes, fasting, in turn, reduces the risk of heart disease.
10. Increases Longevity
Intermittent fasting and restriction of calorie intake have been shown to reduce inflammation and cancer promotion and thus extend life expectancy. Inflammation is an important element of development. Pro-inflammatory factors, such as homocysteine, interleukin 6 (IL6), or C reactive protein (CRP), contribute to the development of atherosclerotic plaque.
Researches conducted by Aksungar et al, have shown the effect of the IF diet on reducing the concentration of the above-mentioned pro-inflammatory factors. The experiment was attended by 40 healthy participants with the correct body mass index (BMI) who fasted during Ramadan and 28 participants, selected in terms of age and BMI index, who did not fast.
Venous blood samples to examine the concentration of the above-mentioned pro-inflammatory factors were collected one week before the start of Ramadan, in the last week of fasting, and three weeks after. The results were positive and all the pro-inflammatory factors were seen to reduce.
Adiponectin is a collagen-like plasma protein, which is involved in glucose level regulation and fatty acid breakdown. It is produced in the adipose tissue. Studies have shown its concentration decreases when we have atherosclerosis, insulin resistance, diabetes, and coronary disease.
The use of the IF diet has shown to increase the secretion of adiponectin from adipocytes. As there is an inverse correlation between plasma adiponectin levels and body weight, the IF diet successfully lowers the body weight, triglyceride, blood glucose level thereby maintaining a healthy body thereby increasing longevity.
An important hormone secreted by adipocytes is leptin. Its concentration is elevated in obese people and is correlated with body mass index (BMI), total cholesterol, triglycerides, blood pressure, and inflammation markers. These correlations were confirmed in studies conducted by Sattar et al.
It was found that the concentration of leptin decreases body weight when using the IF diet. Leptin hyperactivity reduces the risk of atherosclerosis by reducing platelet aggregation and decreasing endothelial cell proliferation.
Summary: intermittent fasting reduces inflammation and cell degeneration thereby increasing longevity.
11. Helps Combat Insomnia
Routine fasting helps the body stay well aligned for sleep in many ways.
Eating at night and having the body engaged in active digestion may create problems for sleep.
Studies show that restricting eating to an 8-12 hour window can help in maintaining normal body weight and avoid high blood sugar and insulin resistance regardless of the nutrient breakdown of the food that we consume within that window period.
Time-restricted eating can strengthen the 24-hour circadian clock. This asserts a strong influence on our sleep. A stronger synchronized circadian clock means an effortlessness to fall asleep, being able to stay asleep and wake up feeling refreshed daily. This consistency and quality in a sleep routine is what we all desire.
The timing and duration of fasting can influence our sleep. Some studies suggest that periodic, short term fasting improves sleep. A study found that periodic fasting reduced waking up at night, decreased leg movements that can disrupt our sleep.
Some studies have also shown that fasting may lessen our REM sleep.
Summary: Intermittent fasting strengthens the circadian rhythm thereby combating insomnia.
12. Reduces Insulin Resistance
Around 1 in 10 people in the US and Canada have type 2 diabetes, which is associated with other serious illness and early death. The main reason for the elevated blood sugar level in the body is insulin resistance. So anything that reduces insulin resistance protects us against diabetes mostly Type 2 diabetes.
Intermittent fasting has shown benefits for insulin resistance and led to an impressive reduction in blood sugar levels. Studies on humans have concluded that in intermittent fasting, fasting blood sugar has reduced to 3-6 percent and fasting insulin has reduced to 20-31 percent.
Another study has shown that intermittent fasting protected against kidney damage which is one of the severe complications of diabetes. Intermittent fasting improves the sensitivity to insulin and protects against fatty liver.
However, there has been an alteration in result in accordance with the gender. While intermittent fasting has shown positive effects in terms of blood glucose level in men, a study showed that 22-day long intermittent fasting worsened the blood sugar control in women. More studies need to be undertaken to show the long term effect of intermittent fasting on blood sugar levels in both the genders.
Summary: Intermittent fasting lowers blood sugar level and reduces insulin resistance.
13. Slows Down Aging
Restricted eating within a time period can improve immune function and maximize the body’s ability to repair cells and DNA. Fasting triggers a cellular process known as autophagy, which is when the cells of the body clear itself of damaged cells, boosting the growth of new, healthy cells.
Autophagy is one way the body maintains more young, functional cells and protects against disease, by removing aged cells that behave dysfunctionally and clearing the body of toxins that build up in older cells.
Intermittent fasting increases the body’s natural production of human growth hormone. The human growth hormone encourages fat burning and protects lean muscle mass, aids in cellular repair, and may help to slow aging.
Fasting can reduce unhealthful inflammation and boost the body’s ability to protect itself against oxidative stress, which is one significant contributor to aging and disease.
Studies in rats have shown that intermittent fasting had quite an effect on lifespan. Rats who fasted every alternate day lived 83 percent longer than the ones who didn’t fast.
Even though it is still not completely proven in humans, it has become popular as it benefits all the health markers that delay aging and increases the lifespan.
Summary: Intermittent fasting by reducing oxidative stress and increasing the natural production of human growth hormone delays the process of aging.
The Final Note
Intermittent fasting as a weight loss strategy has been around for ages in various forms but was highly popularized by different TV shows and books since 2012.
It is an eating pattern that cycles between the period of fasting and eating.
Please do keep in mind that it is not a diet but an eating pattern. As it has now become a trend amongst celebrities and the common people alike, many studies are being conducted to understand its impact on the human body.
Intermittent fasting did show several health benefits over a short and a long period of time. It proved to be an effective way to reduce weight, blood pressure mainly the systolic blood pressure, lower cholesterol, reduce insulin resistance and help in the regeneration of new cells. It proved to be efficient in combating insomnia and increasing longevity. Hence it may be practiced for health benefits with consideration of the method that is best suited for you.