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Intermittent fasting guide

The ultimate beginner’s guide

This guide explains how intermittent fasting can aid weight loss, improve health, and potentially extend lifespan based on scientific studies.

This article is based on scientific evidence, written by experts, and fact-checked by experts.
We look at both sides of the argument and strive to be objective, unbiased, and honest.
Intermittent fasting: The ultimate beginner’s guide
Last updated on January 28, 2024, and last reviewed by an expert on September 20, 2023.

Intermittent fasting (IF) is a hot topic in the health and wellness world right now.

Intermittent fasting: The ultimate beginner’s guide

People are turning to it for weight loss, better health, and a simpler way of life.

Research indicates that it can offer significant benefits for both your body and mind, and might even extend your lifespan.

Consider this your go-to guide for getting started with intermittent fasting.

In this article

What is intermittent fasting (IF)?

Intermittent fasting (IF) is a way of eating where you alternate between periods of not eating (fasting) and eating.

It’s not about the types of food you eat, but rather when you eat them.

So, it’s less of a traditional diet and more of an eating schedule.

Common approaches to intermittent fasting include going without food for 16 hours a day or not eating for an entire 24 hours twice a week.

Historically, fasting is nothing new for humans. Our ancestors, who were hunter-gatherers, didn’t have the luxury of eating whenever they wanted. Sometimes, they had to go without food for long periods.

In that sense, occasional fasting is more in line with our natural rhythms than eating multiple meals every day.

People also fast for various religious and spiritual reasons, like in Islam, Christianity, Judaism, and Buddhism.

Summary: Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. It’s currently very popular in the health and fitness community.

Intermittent fasting methods

There are several ways to practice intermittent fasting, each splitting your day or week into fasting and eating windows.

During fasting times, you generally eat very little or nothing at all.

Here are the most popular methods:

The idea is to cut your calorie intake through these fasting periods. As long as you don’t overeat during your eating windows, you should lose weight.

Intermittent fasting for women: A beginner's guide
Suggested read: Intermittent fasting for women: A beginner's guide

The 16/8 method is generally the easiest to follow, the most sustainable, and the most popular.

Summary: There are various ways to do intermittent fasting, all of which divide your day or week into periods of eating and fasting.

How intermittent fasting impacts your cells and hormones

When you engage in intermittent fasting, your body goes through several changes at the cellular and molecular levels.

For instance, hormone levels shift to make it easier for your body to access stored fat.

Your cells also kick-start repair mechanisms and modify the way certain genes function.

Here’s a closer look at what happens in your body during fasting:

These hormonal and cellular changes contribute to the health advantages of intermittent fasting.

Summary: When you fast, human growth hormone levels go up and insulin levels go down. Your body’s cells also change the expression of genes and initiate important cellular repair processes.

Intermittent fasting as a potent tool for weight loss

The most common reason people turn to intermittent fasting is for weight loss.

Suggested read: 8 science-backed health benefits of fasting

Intermittent fasting naturally limits the number of meals you eat, which often leads to fewer calories consumed.

Moreover, this way of eating affects your hormones in a manner that promotes weight loss.

Besides reducing insulin and increasing growth hormone, it also spikes the release of norepinephrine, a fat-burning hormone.

These hormonal shifts could boost your metabolism by 3.6–14%, making your body more efficient at burning calories.

By affecting both calorie intake and calorie burn, intermittent fasting offers a dual approach for weight loss.

Research confirms its efficacy as a weight-loss method. One review study showed a 3–8% weight loss over a span of 3–24 weeks. It also noted a 4–7% reduction in waist size, indicating a significant loss of harmful belly fat.

Another study revealed that intermittent fasting results in less muscle loss compared to traditional calorie restriction methods.

It’s important to note, though, that the effectiveness of intermittent fasting comes down to calorie control. If you overindulge during your eating windows, you may not see any weight loss benefits.

Summary: Intermittent fasting can increase your metabolic rate while reducing calorie intake, making it a highly effective method for weight loss and reducing belly fat.

Health benefits of intermittent fasting

Numerous research endeavors, encompassing studies on both animals and humans, have delved into the practice of intermittent fasting.

These investigations have unveiled compelling advantages for your well-being, encompassing weight management and the overall health of your body and mind. In fact, it may even contribute to an extended lifespan.

Here’s an overview of the primary health benefits of intermittent fasting:

Keep in mind that research is still in its early stages. Many of the studies were small, short-term, or conducted on animals. Many questions have yet to be answered in higher-quality human studies.

Suggested read: How to fast safely: 10 helpful tips

Summary: Intermittent fasting offers numerous advantages for your physical health and cognitive function. It can lead to weight loss and potentially lower your chances of developing type 2 diabetes, heart disease, and cancer. Additionally, it might contribute to an extended lifespan.

Intermittent fasting makes your healthy lifestyle simpler

Maintaining a healthy diet may sound straightforward, but it often proves to be quite challenging.

One significant hurdle is the considerable effort involved in meal planning and cooking.

Intermittent fasting, however, can streamline this process. With fewer meals to prepare, cook, and tidy up after, it simplifies the approach to healthy eating. It’s no wonder that intermittent fasting has gained popularity among those seeking to enhance their well-being and streamline their daily routines.

Summary: Intermittent fasting stands out for its ability to simplify healthy eating. It reduces the need for extensive meal preparation, cooking, and cleanup.

Who should be careful or avoid intermittent fasting?

Intermittent fasting is not a suitable approach for everyone.

If you are underweight or have a history of eating disorders, it is crucial to seek guidance from a healthcare professional before attempting any form of fasting.

In such cases, intermittent fasting can potentially be harmful to your health.

Is intermittent fasting suitable for women?

There is emerging evidence suggesting that intermittent fasting may not yield the same benefits for women as it does for men.

For instance, a study indicated that while it improved insulin sensitivity in men, it led to worsened blood sugar control in women.

Although direct human studies are limited, research on rats has revealed that intermittent fasting could have adverse effects on female rats, causing emaciation, masculinization, infertility, and disrupted menstrual cycles.

Furthermore, there have been anecdotal accounts from women who experienced menstrual irregularities when they began intermittent fasting but returned to normal when reverting to their previous eating patterns.

Given these considerations, women should exercise caution when considering intermittent fasting. It’s advisable to follow specific guidelines, such as gradually easing into the practice and discontinuing immediately if any issues arise, such as amenorrhea (absence of menstruation).

Suggested read: Is skipping breakfast bad for you?

If fertility concerns or pregnancy are factors in your life, it may be wise to postpone intermittent fasting for the time being. This eating pattern is likely not suitable for pregnant or breastfeeding women.

Summary: Intermittent fasting may not be suitable for everyone. Women, in particular, should approach it with care, considering potential adverse effects and their individual circumstances.

Safety and side effects of intermittent fasting

Hunger emerges as the primary side effect of intermittent fasting.

Additionally, you might experience a sense of weakness, and your cognitive function may not perform at its usual level during this adjustment phase.

However, it’s important to note that these effects are typically transient, as your body adapts to the new eating schedule over time.

For individuals with underlying medical conditions, it is crucial to seek guidance from a healthcare professional before embarking on an intermittent fasting regimen. This is especially critical if you:

That being said, intermittent fasting boasts an impressive safety record. For individuals in good health and with adequate nutrition, there are no inherent dangers in temporarily abstaining from food.

Summary: The primary side effect of intermittent fasting is hunger, though it is generally manageable. However, individuals with specific medical conditions should consult a doctor before starting intermittent fasting to ensure safety and suitability.

Frequently asked questions about intermittent fasting

Here, we address some of the frequently asked questions regarding intermittent fasting:

1. Can I consume liquids during the fast?

Absolutely. You can drink water, coffee, tea, and other non-caloric beverages. Just refrain from adding sugar to your coffee. Small amounts of milk or cream may be acceptable. Notably, coffee can be helpful in curbing hunger during the fast.

48-Hour Fast: How-to, benefits, and downsides
Suggested read: 48-Hour Fast: How-to, benefits, and downsides

2. Is it unhealthy to skip breakfast?

No, it’s not inherently unhealthy. The concern arises when breakfast skipping is accompanied by an overall unhealthy lifestyle. If you ensure that the rest of your daily food intake is balanced and nutritious, skipping breakfast can be a healthy choice.

3. Can I take supplements while fasting?

Yes, you can. However, be aware that certain supplements, like fat-soluble vitamins, may be more effective when taken with meals.

4. Can I exercise while fasting?

Certainly, engaging in workouts while fasting is perfectly fine. Some individuals recommend taking branched-chain amino acids (BCAAs) prior to a fasted workout.

5. Will fasting lead to muscle loss?

All methods of weight loss have the potential to result in muscle loss. To mitigate this risk, it’s essential to incorporate weightlifting into your routine and maintain a high protein intake. Research indicates that intermittent fasting may cause less muscle loss compared to standard calorie restriction.

6. Does fasting slow down metabolism?

No, it doesn’t. Studies indicate that short-term fasting can actually enhance metabolism. However, it’s worth noting that prolonged fasts lasting three or more days may suppress metabolism.

7. Should children fast?

Allowing your child to undertake fasting is generally discouraged and not advisable.

Getting started with intermittent fasting

Chances are, you’ve already engaged in intermittent fasting without even realizing it.

If you’ve ever had dinner, slept through the night, and waited until lunchtime the next day before eating, you’ve essentially fasted for over 16 hours.

For some, this eating pattern feels natural because they aren’t hungry in the morning.

The 16/8 method is often viewed as the simplest and most sustainable form of intermittent fasting. It’s a great starting point to consider.

If you find the 16/8 approach comfortable and feel good during the fasting period, you can explore more advanced fasting methods, such as 24-hour fasts 1–2 times per week (known as eat-stop-eat) or consuming only 500–600 calories on 1–2 days per week (referred to as the 5:2 diet).

Suggested read: 16/8 intermittent fasting: A beginners guide

Alternatively, you can opt for a more flexible approach, fasting whenever it suits you. This entails skipping meals occasionally, especially when you’re not hungry or when time constraints prevent you from preparing a meal.

The key is to experiment with these different approaches and discover the one that aligns with your preferences and fits seamlessly into your daily routine.

Summary: Starting with the 16/8 method is a recommended approach, followed by potential exploration of longer fasting periods. It’s crucial to experiment and find a fasting method that suits your lifestyle and feels enjoyable to you.works for you.

Should you try intermittent fasting?

Intermittent fasting isn’t a mandatory practice for everyone.

It’s merely one of several lifestyle approaches that can enhance your well-being. Prioritizing real, whole foods, engaging in regular exercise, and maintaining healthy sleep patterns remain the fundamental pillars of health.

If the concept of fasting doesn’t resonate with you, there’s no need to dwell on it. You can confidently disregard this article and continue with your established routine.

In the realm of nutrition, there is no universally applicable solution. The most suitable diet is the one that aligns with your long-term preferences and adherence.

Intermittent fasting suits some individuals but may not resonate with others. The most effective way to ascertain where you fit in is by giving it a try.

Should you discover that fasting aligns with your well-being and proves sustainable for you, it can indeed serve as a potent tool for weight management and improved health.

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