Intermittent Fasting: Facts and myths!

Intermittent fasting (IF) has come up as a new way for weight reduction. People have started using it as a method along with other ways for controlling weight. But is it really that useful and beneficial for the body or are there substantial harms that people don’t know about. In todays post we’ll see why you might want to be informed before taking up such a diet.


Intermittent fasting, also known as intermittent energy restriction, is an umbrella term for various meal timing schedules that cycle between voluntary fasting (or reduced calories intake) and non-fasting over a given period. There are many different kinds of fasting similar to different types of diet plan. But all of them have one thing common which is, to eat healthy whenever you eat.

Types of Intermittent Fasting

There are broadly 3 methods to do intermittent fasting. These are alternate-day fasting, periodic fasting and time-restricted feeding.

  1. Alternate-day fasting: Alternate-day fasting involves alternating between a 24-hour “fast day” when the person eats less than 25% of usual energy needs, followed by a 24-hour non-fasting “feast day” period. It is the strictest form of intermittent fasting because there are more days of fasting per week. It has 2 subtypes:

a) Complete alternate-day fasting: No food is taken on fast days

b) Modified alternate-day fasting: In this upto 25% calories of daily requirement is consumed.

2. Periodic fasting or whole-day fastinginvolves any period of consecutive fasting of more than 24 hours, such as the 5:2 diet where there are one or two fast days per week, to the more extreme version with several days or weeks of fasting. On fast days upto 25% calorie of daily required may be allowed to be consumed similar to modified alternate-day fasting.

3. Time-restricted feedinginvolves eating only during a certain number of hours each day. Skipping a meal and the 16:8 diet (16 fasting hours cycled by 8 non-fasting hours) are examples. This schedule is thought to leverage the circadian rhythm.

Benefits of Intermittent Fasting

  1. Weight Reduction

The most important benefit for most people following this is weight loss. Yes there is enough evidence that intermittent fasting helps in weight loss, but it’s subjected to one condition that people should eat healthy whenever they are eating. People might overlook this part of the plan and go on binging on those pizzas or ice-creams.

Additionally, intermittent fasting enhances hormone function to facilitate weight loss. Lower insulin levels, higher growth hormone levels and increased amounts of norepinephrine (noradrenaline) all increase the breakdown of body fat and facilitate its use for energy. For this reason, short-term fasting actually increases your metabolic rate by 3.6-14%, helping you burn even more calories. The basic method is that you are eating fewer meals and hence eating fewer calories or calories that you actually need.

2. Can reduce Insulin resistance

In some preliminary studies it has been found that fasting improves insulin sensitivity of the body and may help in improvement of type 2 diabetes. In human studies on intermittent fasting, fasting blood sugar has been reduced by 3-6%, while fasting insulin has been reduced by 20-31%. A study in diabetic rats showed that it may be protective against kidney damage, one of the most dreaded complication of diabetes.

3. Reduce Inflammation

Several studies have shown that fasting improves bodies capacity to deal with oxidative stress, which is one of the major causes of inflammation increase in the body. It might also help in chronic inflammatory diseases, but more studies are needed on that front.

3. Heart health

Heart diseases are the most common cause of worldwide deaths due to a disease. IF reduces blood sugar levels as well as reduces LDL, aka bad cholesterol, along with reduction in inflammation which are all beneficial towards heart health.

4. Cellular waste management

When we fast, the cells in the body initiate a cellular “waste removal” process called autophagy. This removes the proteins and other cellular elements that have either become old and non-functional or are dysfunctional, which can do more harm that good. Increased autophagy may provide protection against several diseases, including cancer and Alzheimer’s disease, but nothing has been proven as such.

5. Brain health

As the oxidative stress reduces due to IF, the effects of it are also seen in the brain. Several studies in rats have shown that intermittent fasting may increase the growth of new nerve cells, which should have benefits for brain function. There is also release of a hormone called BDNF (brain-derived neurotrophic factor), whose deficiency has been linked to disorders like depression.

6. Hormone level stabilsation


  • Insulin levels: Blood levels of insulin drop substantially, which facilitates fat burning.
  • Human growth hormone (HGH): The blood levels of growth hormone may increase as much as 5-fold. Higher levels of this hormone facilitate fat burning and muscle gain, and have numerous other benefits.
  • Cellular repair process: The body induces important cellular repair processes, such as removing waste material from cells aka autpophagy.

7. Longer Lifespan

Studies in rats have shown that intermittent fasting extends lifespan in a similar way as continuous calorie restriction. In one of them, rats that fasted every other day lived 83% longer than rats who weren’t fasted. Although this is far from being proven in humans, intermittent fasting has become very popular among the anti-aging crowd.

Harmful effects

  1. Growth and Maturation

Children and adolescents who are at the age where there are a lot of functions happening in the body in terms of growth and maturation should completely avoid intermittent fasting. Their body needs calories and different macros and micros for maturation of their brain and other organs. That’s why more and more teenagers need to be educated about the uses and risk of any type of diet or fasting plans to prevent any impairment of growth in them.

2. Mental health

The social media plays a crucial role nowadays in mental health of people especially teenagers. Seeing models and other celebrities with their six packs and perfectly toned body can force a child to do all kinds of things to loose weight or to gain muscle. Simply seeing a friend or relative of same age in good shape might trigger this kind of behaviour and when desired results are attained or when the side effects sets in, which are not publicised on the internet, it might lead to some mood disorders especially depression and anxiety.

Breaking your fast or missing your fasting window by eating either too early or too late could cause anxiety and/or shame. Be alert for these feelings, as they may be signs of something larger, such as disordered eating.

3. Orthorexia

Orthorexia by definition means an obsession with eating foods that one considers healthy. Intermittent fasting could lead to disordered eating behaviours, such as orthorexia, which is defined as an obsession with proper or “healthy” eating. Symptoms include the need to talk about your diet constantly, and a preoccupation with what you will eat next.

4. Sleep disturbances

Researchers have shown that IF can disrupt the sleep cycle, especially the REM sleep, which is the deep sleep. REM sleep is important for the mood, memory and learning capacity.

5. Pancreatic damage

In a study presented at the 2018 annual meeting of the European Society of Endocrinology, Brazilian researchers found that, after a 90-day regimen of alternate-day fasting, lab rats lost weight, but lost muscle and gained stomach fat as well. Further, pancreatic changes suggested an increase in the risk of diabetes.

6. Increase in Cortisol levels

Cortisol is known as the stress hormone in the body as it rises whenever there are periods of stress like anger or fear etc. Sustained high levels of cortisol can cause mood changes and also increase the metabolism more than required which leads to loss of muscles from the body. It also affects brain and thus irritability ensues. Although cortisol is weight reducing hormone but it has paradoxical effect which is increasing fat deposition around the stomach/abdomen area. Cortisol also increases Blood Pressure but under normal conditions it doesn’t sustain it, but due to higher levels than normal it might lead to a problem later.

In Conclusion,

There are various known, not necessarily safe, benefits of doing intermittent fasting. One needs to identify their needs and goals that they are trying to achieve to gain more from this type of fasting rather than doing it as a shortcut for maintaining weight. Even when doing IF one needs to be vigilant about the foods that they eat during the period of non fasting. As mentioned above the food needs to as healthy as in a normal diet plan.

There is some good scientific evidence suggesting that circadian rhythm fasting, when combined with a healthy diet and lifestyle, can be a particularly effective approach to weight loss, especially for people at risk for diabetes. (However, people with advanced diabetes or who are on medications for diabetes, people with a history of eating disorders like anorexia and bulimia, and pregnant or breastfeeding women should not attempt intermittent fasting unless under the close supervision of a physician who can monitor them.)

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