A Beginner’s Guide to Intermittent Fasting

If you check any recent roundup of extremely popular diets, you will surely see intermittent fasting (IF) on the list. Isn’t it great to just be conscious about what you eat only for a couple of days a week? People cannot stop talking about the many health benefits of IF! Most use IF to lose weight, improve health, and simplify lifestyles. It can help you live longer, too (1, 2)! These benefits don’t sound too shabby, do they?

However, similar to other weight loss programs, this approach, which calls for long stretches of time with limited to no food, is not an easy and quick fix. But as per health experts, it can really be effective if it is the right one for you.

IF is not for everyone! It appears that whether or not IF will work for you comes down to human biology. While shorter periods of fasting are generally safe, some of the extended fasting times associated with IF aren’t recommended for certain groups of people.

If you want to know more about IF, read on to get a closer look at what IF is, how it works, its health benefits, and the many ways you can do it. This is a beginner’s guide to intermittent fasting.

What is Intermittent Fasting?

Intermittent fasting is not a diet. It is a timed approach to eating. Unlike other diet plans that restrict calorie intake, IF does not specify the type of foods you must eat or avoid. Rather, it is more focused on the time when you should consume them. It is best described as an eating pattern.

While there are many ways by which you can perform IF, usual IF techniques would involve a 16-hour daily fasting or 24-hour fasting, two times a week. IF is promoted to change body composition by losing weight and fat mass, and to improve markers of health that are related to cholesterol and blood pressure (3). It can also offer physiological benefits over continuous diets for weight loss. It reduces body weight and appetite but not other adaptive responses (4).

The concept of fasting isn’t new at all! In fact, it is often done for spiritual benefits as described in the early texts by Plato, Socrates, and other religious groups (5).

How Does IF Work?

Given the popularity of IF, it is not surprising to know that several different methods of IF have been devised. All of them are effective, but which one fits best will depend on individual factors.

Here are 6 of the best ways to do IF. All of which involve alternating eating and fasting periods within the day or week (6):

1. The 16/8 Method

This technique involves fasting daily for 14-16 hours and limiting your “eating period” to just 8-10 hours. Within this timeframe, you can fit 2-3 meals or more. This technique is also known as the Leangains protocol, which was popularized by Martin Berkhan, a fitness expert.

This method of fasting can be as simple as not eating anything after dinner and skipping breakfast. If you finish your dinner at 8 PM and then don’t eat until noon the next day, then you have technically fasted for 16 hours between meals.

However, if you are the type of person who gets extremely hungry in the morning and loves to eat breakfast, then this can be hard to get used to. You can take water, coffee, and other non-caloric drinks during the fast to help decrease hunger levels. It is extremely important to eat healthy foods during your eating window. This method won’t work if you eat too much junk food or excessive amounts of calories.

2. The 5:2 Diet

If you can’t do fasting every day, this might be the perfect fit for you. The 5:2 diet involves eating normally 5 days weekly and then restricting your calorie intake to 500-600 on the remaining 2 days. This method is also known as the Fast Diet, which was popularized by a British doctor and journalist Michael Mosley.

3. Eat-Stop-Eat

Eat-Stop-Eat requires a 24-hour fast, either once or twice weekly. This technique was popularized by fitness guru Brad Pilon and has been quite popular for years now. You can choose to fast from breakfast to breakfast, lunch to lunch, or dinner to dinner, whichever suits you best. Anyway, the result will be the same, which is a 24-hour fast.

Water, coffee, and other non-caloric drinks are allowed during the fast. If you aim to lose weight, it is very important to eat normally during the eating periods. You have to take the same amount of food as if you had not been fasting at all. Never compensate for the food you missed during fasting.

However, not too many people can easily go with a full 24-hour fast. You don’t need to go all-in right away! You can start with 14-16 hours daily and then move upward.

4. Alternate-Day Fasting

As the name suggests, this method involves fasting every other day. You can allow approximately 500 calories during the fasting periods. There have been several health benefits associated with this technique. However, a full fast every other day is quite extreme, hence not recommended for beginners. You’ll feel extremely hungry several times weekly, so it is quite hard to maintain. It takes time to get used to this fasting method.

5. The Warrior Diet

Popularized by fitness guru Ori Hofmekler, this technique involves eating small amounts of fresh, raw fruits and veggies during the day, then eating one huge meal at night. Basically, you need to fast all day and feast at night within a 4-hour eating period. This is one of the first popular diets to involve IF.

This technique also encourages the consumption of foods quite similar to a paleo diet, which mostly consists of whole, unprocessed foods.

6. Spontaneous Meal Skipping

If you cannot follow a structured IF plan to enjoy weight loss and other health benefits, you can just simply skip meals from time to time, when you don’t feel hungry or too busy to eat. The body is well equipped to handle periods of famine, let alone missing a single meal or two from time to time.

You can skip breakfast occasionally and just eat a healthy lunch or dinner. If you are traveling and can’t find anything that appeals to you, do a short fast.

While all of these techniques should help you lose weight as long as you do not compensate by eating more than usual after the fasting periods, a lot of people find the 16/8 method to be the simplest and most sustainable.

How Can You Benefit from IF?

Now that you have familiarized yourself with the many IF options you can do, it’s time to know the powerful benefits they have for your brain and body. Intermittent fasting, in general, can help you live a healthier and longer life by doing the following:

1. Changing Cell Functions, Genes, and Hormones

When you fast, your body initiates repair processes on a cellular level and modifies hormone levels to access stored body fat easily. The following changes can be observed:

  • Blood insulin levels drop significantly to promote fat burning (7).
  • Blood levels of growth hormone increased up to 5-fold to facilitate fat burning, muscle gain, and several other benefits (8, 9, 10, 11).
  • The body induces cellular repair processes like the removal of waste products from cells (12).
  • There are also beneficial changes in genes and molecules related to longevity and protection against diseases (13, 14).

2. Lowering Insulin Resistance and Risk of Type 2 Diabetes

Who doesn’t know type 2 DM? It has become incredibly common in the past few years! Its main feature is high blood glucose levels in the context of insulin resistance. Anything that decreases insulin resistance should help lower blood glucose levels and protect against type 2 DM.

Good thing, IF has shown major benefits for insulin resistance, which led to an impressive reduction in blood glucose levels. Human studies showed that IF could help reduce fasting blood glucose by 3-6% and fasting insulin by as much as 20-31% (15). Evidence in rats also showed that IF could be protective against kidney damage, which is a common serious complication of DM (16).

3. Reducing Oxidative Stress and Inflammation

We all hear about antioxidants every now and then! It appears to be one of the most talked-about topics in the health industry today, along with the many products being advertised for it.

Oxidative stress, which is an imbalance between the production of reactive oxygen species or free radicals and antioxidant defenses, is known to cause aging and several chronic diseases (17). It involves free radicals, which damages important molecules like DNA and protein (18).

Did you know that apart from taking supplements, you can enhance your body’s resistance to oxidative stress and help fight inflammation by doing intermittent fasting? A growing number of studies can help support these claims (19, 20, 21, 22).

4. Improving Heart Health

Heart diseases have always been one of the world’s biggest killers (23)! Many risk factors are associated with either an increased or decreased risk of heart disease. Animal studies on IF have shown to improve these risk factors, including blood pressure, cholesterol levels, blood triglycerides, blood glucose levels, and inflammatory markers (15, 24, 25, 26).

5. Preventing Cancer

Fasting initiates cellular “waste removal,” known as autophagy (27). Cells break down and metabolize broken and dysfunctional proteins that accumulate inside the cells. Evidence showed that increased autophagy might offer protection against cancer (28).

Fasting also has beneficial effects on metabolism. Animal studies indicate that this can help cancer, too (29, 30, 31, 32)! What’s more, is that IF has also shown to reduce the side effects of chemotherapy on human cancer patients (33).

6. Delaying Alzheimer’s Disease

Alzheimer’s is a common neurodegenerative disease. There is no cure available for this disease yet, so prevention is very critical. A study in rats shows that IF can help delay the onset of Alzheimer’s or reduce its severity (34). Also, in a series of case reports, daily short-term fasts were proven to help improve Alzheimer’s symptoms in 9 out of 10 patients (35). Other studies suggest that fasting may also offer protection against other neurodegenerative diseases like Parkinson’s disease and Huntington’s disease (36, 37).

7. Promoting Brain Health

IF is known to improve several metabolic features, which are important for brain health, this includes less oxidative stress, less inflammation, and low blood glucose levels and insulin resistance. Many studies in rats have proven that IF can help increase the growth of new nerve cells for better brain function (38, 39).

It can also increase the levels of a hormone known as the brain-derived neurotrophic factor (BDNF) (39, 40, 41). A deficiency of this hormone has been implicated in several other brain problems and depression (42). Other evidence revealed that IF could help protect the brain from the damage caused by strokes (43).

8. Prolonging Life Span

One of the most exciting benefits of IF is its ability to extend your lifespan! Rat studies have shown that IF can extend lifespan in the same way as continuous calorie restriction (44, 45). In some of these studies, the effects were dramatic. Rats that fasted every other day lived 83% longer as compared to those who did not fast (46).

Although this is far from being proven in humans, IF has become very popular among the anti-aging crowd.

How Can IF Promote Weight Loss?

Many people are interested in IF for weight loss (47). It can help you slim down by making you eat fewer meals so you will end up limiting your calorie intake. Also, IF enhances hormone functions to facilitate weight loss.

Decreased levels of insulin along with higher levels of growth hormone and norepinephrine will increase the breakdown of fat for energy. For this reason, short-term fasting will help increase your metabolic rate by 3.6-14%, helping you burn more calories (48, 49).

A 2014 review of literature mentioned that IF could cause weight loss of 3-8% over 3-24 weeks (15). People also lost 4-7% of their waist circumference or belly fat. Another review study also pointed out that IF caused less muscle loss as compared to continuous calorie restriction (16).

IF helps you eat fewer calories overall. However, if you eat more than usual after fasting, you may not lose any weight at all.

IF Will Not Suit Everyone

As mentioned earlier, while IF is generally safe for most people, certain groups will have to refrain from fasting.

If you are underweight or have a history of eating disorders IF is not recommended without consulting a doctor first.

Some evidence also showed that IF might not be as beneficial for women as it is for men. One study showed that it improved insulin sensitivity in men, but not in women (50).

Though human studies are not yet available, studies in rats also found that IF can make females emaciated, masculinized, and infertile and cause them to miss menstrual cycles (51, 52). Several anecdotal reports are saying that the menstrual period went back to normal when they resumed their original eating patterns.

If you are having issues conceiving, do not try IF. This eating pattern is also not recommended for pregnant and breastfeeding women.

Should You Try IF?

IF is not something that everybody needs to do, it is just one of the many lifestyle techniques that can help improve your health. Eating real good food, engaging in physical activities, and getting enough sleep and rest are still the most important factors to concentrate on.

There is no one-size-fits-all solution when it comes to weight loss and nutrition. The best diet for you is the one that you can sustain for a long period of time. The only way to know which group you belong to is to try it out with your doctor’s supervision.

How Should You Start IF?

If you are ready to try fasting, the following tips should help you make your experience as easy and successful as possible:

1. Know Your Goals

Every person who tries IF has a goal in mind. What is yours? Do you want to lose weight, or are you aiming to improve your overall health? Your ultimate goal should help you determine which fasting method is the best to use and work out your nutritional and caloric needs.

2. Choose A Method

As discussed earlier, there are 6 potential methods that you can try when fasting for health reasons. You must pick a plan that you can stick with and suits your preferences. Typically, you must do one fasting method for a month or longer to see if it will work for you before trying a new one.

When choosing a method, you should remember that you do not need to eat a certain type or amount of food or avoid foods altogether. However, following a healthful, vegetable-rich, high-fiber diet during your eating window can help bring greater progress.

3. Check Your Caloric Needs

As we keep on saying, there are no dietary restrictions when fasting, but this does not meal calories do not matter. If you want to lose weight, you have to create a deficit. You must consume less energy than you use.

There are several tools available to help you work out your caloric needs and know how many should you consume daily to lose weight. You can also speak to a healthcare provider or a dietitian for guidance.

4. Figure Out A Meal Plan

Planning what to eat during the day or week can help you big time! It doesn’t have to be very restrictive. You just have to include proper nutrients into your diet and consider your calorie intake. Meal planning will make it easier for you to stick to your calorie count while ensuring you get the necessary food on hand for your meals and snacks.

5. Make the Calories Count

You have to understand that not all calories are the same. While the above-mentioned methods do not set restrictions on how many calories you can consume when fasting, it is very important to consider the nutritional values of the foods you are taking.

You have to aim for nutrient-packed foods! Though you may not have to abandon junk food entirely, you should still eat them in moderation and focus on healthier options to gain the most benefits.

The Bottomline

Fasting is actually a natural part of the human life cycle. Many have fasted unknowingly throughout their lifetimes by skipping breakfast or eating an early dinner. While more structured methods may work well for most people, some may not benefit from them at all.

While an average person will likely experience no or minimal side effects, people with certain medical conditions or who are taking medications should consult a doctor first before trying IF.

Remember, you do not have to exclude certain foods from your diet; you should just aim to eat a balance of protein, fiber, and vegetables. Drink plenty of fluids too!

If intermittent fasting makes you feel great, and you find it easy to maintain, it can be a powerful tool to lose weight and improve your overall health.


(1) https://www.sciencedirect.com/science/article/pii/S193152441400200X
(2) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3946160/
(3) https://www.hsph.harvard.edu/nutritionsource/healthy-weight/diet-reviews/intermittent-fasting/
(4) https://www.sciencedirect.com/science/article/pii/S0303720715300800
(5) https://www.sciencedirect.com/science/article/pii/S089990071630226X
(6) https://academic.oup.com/nutritionreviews/article-abstract/73/10/661/1849182
(7) https://www.ncbi.nlm.nih.gov/pubmed/15640462
(8) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC329619/
(9) https://www.ncbi.nlm.nih.gov/pubmed/1548337
(10) https://www.ncbi.nlm.nih.gov/pubmed/12425705
(11) https://www.ncbi.nlm.nih.gov/pubmed/2355952
(12) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3106288/
(13) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2622429/
(14) https://www.ncbi.nlm.nih.gov/pubmed/24048020
(15) https://www.sciencedirect.com/science/article/pii/S193152441400200X
(16) https://www.ncbi.nlm.nih.gov/pubmed/17316625
(17) https://www.ncbi.nlm.nih.gov/pubmed/15123782
(18) https://www.hindawi.com/journals/bmri/2014/761264/
(19) https://www.ncbi.nlm.nih.gov/pubmed/17291990/
(20) https://www.sciencedirect.com/science/article/pii/S095528630400261X
(21) https://www.ncbi.nlm.nih.gov/pubmed/23244540
(22) https://www.ncbi.nlm.nih.gov/pubmed/17374948
(23) https://www.cdc.gov/nchs/fastats/leading-causes-of-death.htm
(24) https://www.sciencedirect.com/science/article/pii/S0104423013000213
(25) https://ibimapublishing.com/articles/ENDO/2014/459119/
(26) https://www.ncbi.nlm.nih.gov/pubmed/19793855
(27) https://www.ncbi.nlm.nih.gov/pubmed/21106691
(28) https://www.ncbi.nlm.nih.gov/pubmed/19524509
(29) https://www.ncbi.nlm.nih.gov/pubmed/16126250
(30) https://www.ncbi.nlm.nih.gov/pubmed/3245934
(31) https://www.ncbi.nlm.nih.gov/pubmed/22323820
(32) https://www.ncbi.nlm.nih.gov/pubmed/11835290
(33) https://www.ncbi.nlm.nih.gov/pubmed/20157582/
(34) https://www.ncbi.nlm.nih.gov/pubmed/17306982
(35) https://www.aging-us.com/article/NjJf3fWGKw4e99CyC/text
(36) https://www.ncbi.nlm.nih.gov/pubmed/10398297
(37) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2622429/
(38) https://onlinelibrary.wiley.com/doi/full/10.1046/j.0022-3042.2001.00747.x
(39) https://www.ncbi.nlm.nih.gov/pubmed/11220789
(40) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC151440/
(41) https://www.ncbi.nlm.nih.gov/pubmed/16011467
(42) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3022308/
(43) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2844782/
(44) https://www.sciencedirect.com/science/article/pii/S0047637400001093
(45) https://academic.oup.com/geronj/article-abstract/38/1/36/570019
(46) https://www.karger.com/Article/Abstract/212538
(47) https://www.ncbi.nlm.nih.gov/pubmed/25540982
(48) https://www.ncbi.nlm.nih.gov/pubmed/2405717
(49) https://www.ncbi.nlm.nih.gov/pubmed/10837292
(50) https://www.ncbi.nlm.nih.gov/pubmed/15833943
(51) https://www.ncbi.nlm.nih.gov/pubmed/19127293
(52) https://www.ncbi.nlm.nih.gov/pubmed/17569758


We will be happy to hear your thoughts

Leave a reply