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Intermittent fasting is one of the most popular diets to promote quick weight loss. It involves a cycle of eating followed by a cycle of fasting. The diet doesn’t tell you what to eat but when to eat. One well-known form of intermittent fasting is the 16:8 method where it has an eating period of 8 hours followed by fasting for 16 hours.

Why is fasting important?

In ancient times humans have been fasting for thousands of years after sunsets down because it was dark outside and they won’t be able to search or hunt for food.

Fasting is common for religious reasons. In Islam, Christianity and Buddhism fasting during a specific time period in a year is common.

Extended periods of fasting are easy to handle by our body. All sorts of processes in the body change fast. Important cellular repair processes, reduction in blood sugar levels and insulin levels and increase in human growth hormone takes place.

This is simple yet effective way to restrict calories and burn fat..!

How does intermittent fasting work?

Everyone fasts during sleep, intermittent fasting just extends the fast a little longer.  During extended fasting, the period body uses excess fat which is stored for producing energy. Let’s see how this works.

Food gives us the energy for daily activities. The stored energy can be used immediately or stored for later use. The hormone involved in the storage of this energy is insulin. Insulin rises when we eat and helps to store excess energy.

Carbohydrates are broken down into glucose units which are linked into long chains to form glycogen and are stored in muscle or liver. When the storage space for carbohydrates is exceeded the liver turns excess glucose into fat. This process is known as de-novo lipogenesis. Some of this newly formed fat is stored in the liver and the rest are exported to other fat deposits in the body. So there are two storage systems that exist in our systems are as glycogen and body fat.

During the fasting period, insulin levels fall so the body starts to burn the stored energy and when blood glucose level falls glycogen is the most easily accessible energy source. This is broken down into glucose molecules to provide energy and later stored glycogen is used. Production of energy by breaking down stored fat is common.

Types of intermittent fasting:

Intermittent fast has two windows,

Eating window:

It is the calorie intake period by eating healthier and filling foods with low calories is preferred according to the person BMR.

eating disorder

Fasting window:

In this, the zero-calorie intake is preferred and drinks with no calories such as water, black tea, black coffee, lemon tea can be taken.  

Further, there are methods of intermittent fasting.


16:8 method:

This involves a fast for 16 hours and 8 hours of eating window time when we can consume two or three meals. It’s a common method.

12 hour method:

This method is preferable for beginners. This involves a 12 hour eating period followed by 12-hour fasting. When they adapt to this method it will be much easier to follow the 16:8 method for fasting.

5:2 method :

In this diet, they are allowed to eat healthier food for 5 days a week and reduced calorie intake for the other 2 days (calorie intake must be below 500 calories)

Warrior diet:

This method follows 4 hour eating period when we can have one big meal or two meals and follow by a 20 hour fasting period.

Alternate day fasting:

During eating day they are allowed to intake normal foods and on fasting days solid foods need to be avoided

24 hour fast:

This method is also known as eat stop eat a diet where people are not allowed to eat solid food for 24 hours and can eat normally on other eating days.

Things to follow during fasting:

Avoid sugars and refined grains:

Consume fruits, vegetables, lentils, whole grains, lean proteins and healthy fats.

Avoid  snack in-between meals:

To build muscle tone and stay active during day so body can burn fat between meals.

Stay hydrated:

It’s important to intake a sufficient amount of water and other low-calorie drink to aid fat burning. Eat high volume foods which fill up and have fewer calories like popcorn, raw vegetables and fruits containing high water content.


Exercise plays a major role. It helps to burn our calories and fats. Some sort of physical activity is needed to keep active along with diet.

Points to remember before fasting:

  • One can consume up to 50 calories during the fasting period.
  • You can’t consume as many calories and unhealthy foods during the eating period, when you are fasting for 16 hours stick to a proper and mindful diet.
  • One cheat day can be taken to avoid fasting stress
  • It’s not starvation it is fasting. Fasting is a voluntary practice to control hunger.
  • Exercise during the eating period and meditate during the fasting period to control hunger.

Drinks that can be taken during fasting time are water, black coffee, black tea, cinnamon tea. Alcoholic beverages need to be strictly avoided during this fast.

Benefits of intermittent fasting:

Lose weight and visceral fat:

Intermittent fasting helps to eat fewer meals so we will end up taking fewer calories. Intermittent fasting enhances hormone function and aids in weight loss. It lowers insulin levels, higher HGH levels and increases the amount of epinephrine and these all will increase the breakdown of body fat and use it for producing energy. So the calories intake during the eating period will burn down along with fat during the fasting period to produce the required energy for the body.

Reduce insulin resistance:

Intermittent fasting reduces insulin resistance hence it lowers the risk of type 2 diabetes mellitus. Lower the insulin resistance lower the blood pressure.

Reduces oxidative stress and inflammation in body:

Oxidative stress is one of the steps toward ageing and many chronic diseases. So intermittent fasting enhances the body resistance to oxidative stress. Calorie restriction will reduce inflammation levels during the fasting period.

Supports healthy heart:

When insulin levels fall, there is a risk of dangerous cardiovascular disease such as congestive heart failure decreases. This is important because patients with type 2 diabetes mellitus are more likely to die from heart disease than other persons.

Lowers cholesterol:

Fasting combined with exercise reduces the triglycerides in body which reduce the LDL cholesterol level.

Changes the function of hormones and cells:

  • During fasting, the body changes hormone levels to make stored body fat accessible and initiates the cellular repair process.
  • Human Growth Hormone levels increase and promotes fat burning and muscle gain.
  • Body induces important cellular repair process by removing damaged cells which is known as autophagy.

Increased life span:

Fasting aids in beneficial changes in genes and molecules related to longevity. It helps the body to build resistance against age-related diseases.


90 minutes (3 hours)Blood glucose levels increase depending on the last meal.
4 hoursThe food gets digested which will decrease blood glucose levels and produce insulin.
12 hoursIt is the standard fast period for most people and the body is still consuming glucose left out.
16 hoursAs the glucose depletes, the body uses the fat as fuel. Workout during this time period will help in boosting the fat burning process.
20 hoursThis is the peak fat-burning period. More fat is burned and ketosis begins. We can take a low carb diet to balance the levels.
24 hoursThe fat burning continues and autophagy begins in this time period.

Who should not fast?

  1. Children under 18
  2. Pregnant and lactating women
  3. Underweight ( BMI < 18 )
  4. Anorexia
Fetal Alcohol Syndrome

Conditions which need medical supervision during this diet

  1. Persons with diabetes mellitus – type 1 and 2
  2. A person who have high uric acid
  3. A person with heart disease and liver disease


When you are following intermittent fasting staying hydrated is a must and following a healthier diet is recommended otherwise it may lead to these side effects.


Most common side effect of fasting but can be compensated with having low calorie drinks.

Headaches :

It is most common for beginners due to hunger.

Dizziness :

It occurs due to having very restricted diet without sufficient nutrients and minerals needed for body to function.

Refeeding syndrome :

This is rare and happens when people fast for 5-10 days, especially in malnourished patients. These are potentially fatal shifts between fluids and electrolytes.

To sum up, there are several diets that people can follow for weight loss. Intermittent fasting is one of those effective ways for losing weight. It just helps us to know when to eat and not what to eat. Hunger and dehydration are a major side effect of this diet but which can be substituted by having water and low-calorie drinks. Losing weight is not a big challenge until you are consistent in your diet and workouts., it can be any diet but being regular and having healthier foods will help us to lead a healthier lifestyle.

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Dr. Reshma

I am a dental surgeon and cosmetologist. I love to take care of pets, draw mandala and travel. My area of interest is aesthetic medicine and forensics.

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