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Fasting and Its Implications on Health

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Fasting and Its Implications on Health

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Intermittent fasting is one of the best diet regimens. This article talks about intermittent fasting and how it benefits human health.

Medically reviewed by

Dr. Preetha. J

Published At May 21, 2018
Reviewed AtMarch 27, 2023

What Is Intermittent Fasting?

Intermittent fasting is a diet that involves alternating periods of fasting (either without meals or with a large reduction in calories) and periods of unrestricted eating. It is advocated for changing body composition by losing fat mass and weight, as well as improving health markers linked to diseases, including blood pressure and cholesterol levels. The origin of fasting can be traced back to traditional fasting, which is a worldwide rite used for health or spiritual reasons, according to some religious organizations.

Fasting usually involves refraining from food and beverages for a period of time ranging from 12 hours to one month. It could require staying away or only allowing a certain amount of food and drink. Physiological changes caused by long-term very low-calorie diets may allow the body to adapt to the calorie restriction, preventing future weight reduction. Intermittent fasting helps to solve this issue by cycling between a low-calorie diet for a short period of time and regular eating, which may prevent these adaptations. In terms of weight loss efficiency, however, research does not consistently suggest that intermittent fasting is preferable to continuous low-calorie diets.

What Are the Different Types of Fasting?

Alternate days fasting throughout the day with a certain frequency each week or for a specific time frame are the most prevalent techniques. The following are the various types of fasting:

  • Alternate-Day Fasting: Alternating between days with no food restrictions and days with one meal that supplies around 25 % of daily calorie requirements.

  • Whole-Day Fasting: Complete fasting or up to 25 % of daily calorie demands one to two times each week, with no food restriction on the other days.

  • Time-Restricted Feeding: Each day, stick to a meal plan and fast for a set amount of time.

How Does Intermittent Fasting Work?

This type of fasting can be accomplished and done in a variety of methods, but they all revolve around establishing regular eating and fasting schedules. You could, for example, only eat for eight hours a day and fast the rest of the time. You could also choose to eat only one meal per day, two times per week. You can choose from a range of intermittent fasting schedules.

After several hours without eating, the body's sugar stores are depleted, and it begins to burn fat. This is referred to as metabolic switching. Intermittent fasting is in contrast to the typical eating habit of most people, who eat continuously throughout the day. If someone eats meals three times a day, plus snacks, and does not exercise, they are consuming calories rather than burning fat stores in the body every time they eat and have food. Intermittent fasting works by extending and increasing the duration of your body burning off the calories from the food you consumed and starts burning fat. This has lots of benefits for your health.

What Are the Benefits of Intermittent Fasting?

The benefits include:

  1. Decreased neurodegeneration.

  2. Stimulates growth hormone.

  3. Weight loss with prevention of lean mass.

  4. Improved blood pressure.

  5. Improved insulin sensitivity.

  6. Increased PGC-1 alpha.

  7. Gets the body rid of excess fluid.

  8. Cancer prevention.

  9. Reduced oxidative stress.

  10. Stimulates brain-derived neurotrophic factor.

  11. Improved cognition.

Here are some intermittent fasting benefits research has revealed so far-

  • Thinking and Memory: According to research, intermittent fasting increases working memory in animals and verbal memory in adults.

  • Heart Health: Blood pressure, resting heart rates, and other heart-related indicators improved after a brief fast.

  • Physical Performance: In young boys, fasting for 16 hours resulted in fat reduction while maintaining muscle mass. Mice that were fed on various days showed more endurance when running.

  • Diabetes and Obesity: In animals, intermittent fasting has been found to prevent obesity. Obese adults who fasted intermittently lost weight in six short studies.

  • Tissue Health: In animals, intermittent fasting reduces tissue damage after surgery and improves results.

Research has also found that fasting dramatically increases longevity and reduces health risks like,

People who are well-fed have more chance of weight gain and insulin resistance which increases the risk of,

Glucose and fats are body fuels for energy. If we restrict glucose intake, the body will utilize fats for energy supply.

Why Are You Not Shedding Weight with Intermittent Fasting?

The most common reasons are:

  • Eating the wrong type of food.

  • Not drinking enough water.

  • Not eating enough food.

  • Having a fasting window is too short.

  • Keeping on breaking the fast.

  • Not eating enough protein.

How to Maximize and Increase Your Weight Loss during Intermittent Fasting?

The following methods help to maximize the weight loss during intermittent fasting -

Exercise: Exercising while fasting may be worth a try, but you must remember to do it safely.

Meal Preparation: Even after you finish the diet, meal preparation will help you keep track of your calorie intake and maintain and follow up with a healthy lifestyle.

Supplements: Supplements make it simple to lose weight. However, before beginning any fat-loss product, talk to your doctor about your alternatives.

Is Intermittent Fasting Safe?

Some people use intermittent fasting to lose and reduce weight, while some use it to treat chronic illnesses, which include irritable bowel syndrome, high cholesterol, or arthritis. Intermittent fasting, on the other hand, is not for everyone.

Before attempting intermittent fasting or any other diet, have an appointment with your primary care physician or consultant. Some individuals should avoid or take precautions before experimenting with intermittent fasting:

  • Small children and teenagers under the age of 18.

  • Women who are pregnant or who are breastfeeding.

  • Patients with diabetes or other related blood sugar issues.

  • History of an eating disorder in the past.

Those people who are not in these categories and can safely undertake intermittent fasting can keep doing it indefinitely. It can be a lifestyle shift with numerous advantages.


Intermittent fasting is a good way to lose weight, but it is not a quick fix. When it comes to intermittent fasting, it can take up to eight weeks to see considerable weight loss. You must be committed to making intermittent fasting work for you. You will have to put forth the effort. Always try to keep in mind that intermittent fasting can have a variety of impacts depending on the individual. Before beginning the regimen, consult your doctor, and also if you have unusual anxiety, headaches, nausea, or other symptoms after you begin intermittent fasting.

Frequently Asked Questions


What Can Be the Implications of Fasting?

Fasting can increase stress levels and can cause sleepless nights. Starving or fasting can increase cortisol levels in the body. Fasting can also cause physical symptoms, such as headache, acidity, and heartburn.


Does Fasting Cause Harm to Your Body?

Yes, fasting can be extremely harmful to your body. However, intermittent fasting can be beneficial to some people. Fasting for longer hours can cause severe side effects. It can cause more fat production in the body. Fasting can cause side effects, such as heartburn, acidity, and headaches.


What Are the Drawbacks of Fasting?

The drawbacks of fasting can include the following:
- It may cause overeating.
- Increase in stress and cortisol levels.
- It may lead to other eating disorders. 
- It can cause alterations in mental status. 
- It can cause an overall reduction in energy levels.


What Are the Three Major Types of Fasting?

The three major types of fasting may include:
- Intermittent fasting or time-restricted fasting.
- Calorie-restricted fasting.
- Periodic fasting.


For Whom is Fasting Not Suitable?

Fasting may not be suitable for: 
- Patients with conditions such as diabetes or other heart conditions.
- Patients who are on various medications.
- Pregnant women or lactating mothers.
- Children or old people.


Is It Alright to Fast for Three Continuous Days?

Fasting for three continuous days may suit someone and may not suit others. However, it is not medically advisable to fast for three days as it can lead to complications, such as dehydration and acidity. This situation may be possible for some, yet it is highly risky.


What Is the Maximum Duration Upto Which One Can Fast Safely?

There is no defined duration for this. Medically anywhere between 24 hours to three days is acceptable. However, this range varies from person to person. Beyond this time period, the ill effects of fasting can set in.


Can You Workout During Fasting?

Yes, one can workout during fasting. Exercising while fasting can boost fat loss as the fat cells are broken down to give energy. However, care should be taken not to exhaust too much as it may lead to weakness.


What Is the Best Thing to Drink While Fasting?

One should be well-hydrated while fasting. Hence, some of the best things to drink while fasting may include:
- Mineralized water.
- Sparkling water.
- Beverages, such as tea or coffee, without sweeteners.
- Coconut water.


What Is the Safe Margin of Intermittent Fasting?

The safe margin for intermittent fasting is considered to be 12 hours. However, it is said that if a person fasts between 10 to 16 hours, the fat stored in the body starts getting consumed. This can cause weight loss.


What Are the Negative Consequences of Intermittent Fasting?

The negative consequences of intermittent fasting may include the following:
- Food cravings and hunger.
- Headache.
- Mood swings and other mental changes. 
- Extreme fatigue and low energy.
- Disturbances in sleeping pattern.


How Many Days a Week Can We Do Intermittent Fasting?

Intermittent fasting is a type of fasting in which a person can fast completely for a few hours in a day. A person can generally do intermittent fasting for up to 12 hours daily. It is advisable to practice intermittent fasting up to five days a week.


What Do You Mean by Dirty Fasting?

Consuming excessive amounts of calories during fasting is known as dirty fasting. It is considered dirty fasting if a person consumes up to 100 calories during fasting. It is the opposite to clean fasting, in which a person does not consume any calories during fasting.


Can Intermittent Fasting Ruin a Person's Metabolism?

Yes, practicing intermittent fasting for longer durations can alter a person's metabolism. Continuous practice of intermittent fasting can slow down a person's metabolism. Hence, the desired weight loss goals may not be achieved.
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Dr. Sumaiya Jamil
Dr. Sumaiya Jamil

General Practitioner


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