All About Intermittent Fasting – Types, Benefits & Side Effects

Intermittent fasting is not just a diet; it is, in fact, a pattern of eating. It doesn’t involve changing what you eat; it changes the way you eat your food. Though it is a new fitness trend, the practice of going without eating and drinking for a limited period has been a part of various religions and cultures throughout the world.

Not only can intermittent fasting help you lose weight, but it is also beneficial for reducing insulin resistance, lowering the risk of heart disease and improving brain function.


Let us learn some more about intermittent fasting, its potential benefits, and side effects.

What is intermittent fasting?

Intermittent fasting is a term used for an eating pattern that involves fixed periods for fasting and for eating. It does not limit your choice of foods, but it limits the time that you can eat it.

This process of fasting is not as complicated as it sounds. Most of us fast for at least 10 hours every day when we sleep. Intermittent fasting involves extending this period for a little longer.

Types of intermittent fasting

There are six primary ways in which you can follow intermittent fasting.

1. Time-restricted fasting (16/8 method)

This method involves fasting for up to 16 hours, and it allows you to eat for eight hours every day. The fasting period starts at night and lasts until the middle of the day.

So, it involves skipping breakfast. For people who follow this pattern, lunch in their first meal of the day and they can eat for the next eight hours.

2. Modified fasting (5:2 method)

This method allows you to eat 25 percent of your recommended calories for the two days of the week that you are fasting. You can eat regularly on the five other days of the week.

3. Alternate fasting

This method allows you to switch between periods when you can have zero calorie foods for periods that you can have a healthy diet. The periods can vary from person to person, but in most cases, it is 12 hours.

Intermittent fasting infographic - 2

4. Eat stop eat

This method involves fasting for 24 hours and eating regularly for the next 24 hours. Water, coffee, and non-alcoholic drinks are allowed during the fasting period but no food.

5. Warrior diet

This diet involves fasting through the day and then eating a huge meal at night. The method allows you to eat small amounts of fruits and vegetables during the day and then you can have a big meal during a four-hour window at the end of the day.

This meal, however, should consist of healthy unprocessed food.

6. Spontaneous meal skipping

According to this diet, it is a myth that your body will go into starvation mode if you skip meals. This diet allows you to skip meals when you are not hungry or if you do not have the time to eat.

How does intermittent fasting work?

Fasting is not an unnatural process. We instinctively fast when we are not well. Humans have been fasting for centuries, sometimes out of necessity due to lack of food and sometimes due to religious beliefs.

According to research, the process of fasting helps us in many ways. During a trial published in the American Journal of Clinical Nutrition, researchers observed that short-term alternate day fasting could help obese individuals lose weight and reduce coronary artery disease risk (1).

It leads to lowered levels of oxidative stress to cells in the body. It also improves our body’s ability to deal with stress at the cellular level. Intermittent fasting helps to activate the cellular stress response pathways of our body.

These act like stimulants for our body. Over a period, this process makes our body less susceptible to cellular aging and disease (2).

According to some experimental studies, intermittent fasting can improve the lipid profile by decreasing inflammatory responses (3).

Fasting also enhances growth hormone secretion, and it helps lower blood sugar and insulin levels in the body (4, 5). Some other studies have also shown that intermittent fasting can help you live longer.

According to some animal studies, fasting can also help in extending lifespan.

Health benefits of intermittent fasting

The health benefits of intermittent fasting are not restricted to just weight loss; it also helps slow down aging and lowers the risk of heart disease and diabetes. These are some of the health benefits of intermittent fasting.

1. Helps you lose weight and keeps it off

During intermittent fasting, you eat fewer meals. So, unless to eat as much or more during the other meals, you will consume fewer calories and lose weight.

It also improves hormone function which helps increase the metabolic rate. According to studies, it can enhance the metabolic rate by 3.6 to 14 percent (6).

According to another study, intermittent fasting caused less muscle loss as compared to other diets (7).

One study compared the effects of weight loss between the low-calorie diet and intermittent fasting. The results of the study showed that intermittent fasting is more minimizing weight regain after a year (8).

Intermittent fasting infographic - 1

2. Lowers your risk of type-2 diabetes

According to a study done at the University of Southern California, fasting diets trigger the production of new pancreatic cells to replace dysfunctional ones and stabilize blood glucose (9). This reverses insulin resistance and depletion.

Intermittent fasting is also helpful in lowering the risk of developing type-2 diabetes.

According to studies, intermittent fasting can reduce the levels of blood sugar by 3 to 6 percent and that of fasting insulin by 20 to 31 percent (10).

3. Reduces inflammation and oxidative stress

Long-term inflammation can lead to weight gain, stubborn belly fat and other diseases, while oxidative stress can lead to aging and other ailments. Studies show that intermittent fasting can enhance the body’s resistance to oxidative stress and inflammation (11).

Fasting produces an anti-inflammatory effect which helps prevent weight gain, aging, and other related diseases.

4. Lowers risk for cardiovascular disease

According to the Centers for Disease Control and Prevention, about 60000 people die of heart disease in the US every year (12). You can reduce your risk of

heart disease by following a healthy lifestyle. According to a study, intermittent fasting is an effective way to lower the risk of heart disease as it helps to lose weight, reduce blood pressure, total cholesterol, LDL cholesterol, and triacylglycerol concentration (13).

5. Can slow down the aging

According to a study done at Harvard, the food-free period during intermittent fasting manipulates the energy-producing mitochondria of the cells and increases the lifespan (14).

Some animal studies have also shown that intermittent fasting can extend lifespan in rats (15).

6. Keeps your brain healthy

Intermittent fasting promotes brain health and reduces the risk of developing neurodegenerative illnesses like Alzheimer’s and Parkinson’s.

The fasting period helps the body to get rid of the glycogen stores, and this helps burn fat instead of sugar. This fat burning produces ketones which boost the energy levels and get rid of brain fog.

According to a 2014 report, therapeutic interventions that included short-term fasts helped in the reversal of the cognitive decline in patients with Alzheimer’s (16).

7.  May help prevent cancer

Fasting is known to have a beneficial effect on metabolism which may help prevent cancer. Numerous animal studies have shown that intermittent fasting can help prevent cancer (17, 18).

Some other studies have also shown that fasting helps reduce the side effects of chemotherapy (19).

Side effects of intermittent fasting

While intermittent fasting has many health benefits, it can have some side effects as well.

1. Heartburn

Some people experience heartburn during the fasting process. This happens because our body releases acids during certain times of the day based on the regular eating patterns.

When you change your eating pattern, this excess acid can lead to heartburn.

2. Hunger and cravings

Ghrelin, the hormone responsible for hunger, peaks around meal times. The hormone continues to rise around the same time even when you are fasting, and this leads to hunger and cravings.

3. Headaches

Mild headaches are common when the body is trying to adjust to a new eating schedule. Drink more water and keep yourself hydrated.


Common questions about intermittent fasting

Is intermittent fasting safe for everyone?

No. People who have a history of eating disorders or are underweight should avoid intermittent fasting. Children under 18 need extra nutrition to grow, so do pregnant and lactating women. They should not try intermittent fasting.

If you have a medical condition like type-1 or type-2 diabetes, low blood pressure and high uric acid and are taking medication, consult with your doctor before you fast.

Are liquids allowed during fast?

Yes, you can continue to drink water, coffee, tea and other non-alcoholic drinks while fasting. It is essential to keep yourself hydrated.

Can I exercise during intermittent fasting?

Yes, you can continue to exercise during the fasting period. During this time your body will burn fat to provide you with energy.

Will fasting put me in starvation mode?

No. In fact, fasting improves your metabolic rate.

What are the top tips for fasting?

  • Drink water and stay hydrated.
  • Keep your energies up with tea and coffee.
  • Don’t binge after fasting.
  • Stay busy to avoid cravings.
  • Give yourself a month.

Final thoughts on intermittent fasting

Intermittent fasting doesn’t change what you can eat but how you eat. It can benefit your health in many ways. You can choose from the several styles of intermittent fasting that are commonly prevalent. However, if you are under medication do check with your doctor before you start fasting.


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