Intermittent Fasting: Myths and Facts
*The following information is not intended as medical advice. We always recommend talking to your doctor before starting a new diet.
You may have heard about intermittent fasting (IF) from a nutrition influencer, weight loss guru or a friend. It seems that IF has taken over as a huge nutrition trend in the past few years. Although it may seem like a modern trend, cultures and religions all over the world have been fasting for centuries. For example, Muslims fast each day during the religious period of Ramadan, which is currently taking place.
So why is intermittent fasting so popular and is it really all it’s cracked up to be? Is it a miracle cure for your ailments or the nutrition solution you’ve been waiting for? In this blog post I want to unpack the truths and bust the myths behind IF in order to leave you with accurate information, so you can decide if it’s right for you.
Skipping Breakfast Means I’m Fasting, Right?
Depending on the type of fasting you’re engaging in, this may or may not be true. Intermittent fasting, reduced meal frequency or time-restricted eating are all similar terms which describe a period of avoiding food, followed by a period of eating. This can be done in a variety of ways. Some people choose to fast one day and eat the following day, called an alternate fast. Others prefer to keep a consistent schedule and limit the hours in the day when they eat. The most common example would be an 8 hour eating window, followed by 16 hours without eating (8/16). Some people choose to extend the eating window to 10 hours, and fast for only 14 (10/14).
Breakfast tends to be the meal that is most commonly skipped in an 8/16 or 10/14 fast since it is often eaten alone and at home. This method allows you to continue eating lunch and dinner with your friends or family.
Won’t I Be Hungry When I’m Fasting?
It’s likely you’ll be hungry for the first couple days or week as you’re adjusting to a new way of eating, but this is to be expected. However, after this period, the data suggests that hunger levels tend to remain steady or may even decrease after a period of IF (1). Some studies reported that hunger may increase a little bit before bed time (2).
Intermittent Fasting is the Same as Any Other Diet
This one is partially true. The general principle behind any diet is that you are restricting your calories compared to what you would typically eat and compared to the calories you are expending each day. In this sense, IF is like other diets because you are restricting your caloric intake to a small time period, meaning you will likely be eating less than you normally would be.
Most of the health benefits that come from IF, like weight loss, lower blood pressure or reduced blood glucose levels are due to less calories being consumed (3). However, several studies have shown additional benefits to IF that haven’t been seen with general caloric restriction (3). In fact, some of these health benefits have been shown to occur regardless of any weight loss.
One of the theories behind why this happens is related to IF’s impact on the circadian rhythm (3, 4). The circadian rhythm has to do with the regulation of our body over a 24-hour period, from wake and sleep, to eating, hunger, mood and hormone release. It has been shown that IF can impact genes that are related to the circadian rhythm and that IF can also improve sleep quality and duration (3). This means that even if you aren’t using IF to lose weight, it may have a positive influence on your body by way of regulating your daily cycle.
Intermittent Fasting is the Magic Weight Loss Solution
It may not be magic, but it can be a solution for some people. As mentioned above, IF can be very effective in generating weight loss. Most studies done on IF have been at least 8 weeks long and these showed weight loss of about 4-8% compared to baseline weight (5). Longer studies from 12 to 26 weeks generally showed higher levels of weight loss from 8-13% (5).
When studies have compared IF to a general calorie restricted diet, they have usually found similar results in terms of weight loss (1). In the studies that followed up with participants after a period of time, they found that both groups re-gained a similar amount of weight too (1).
Drinking Water While Fasting Will Cancel Out Any Benefits
This is a complete myth! Water is essential for many functions in our body like circulating nutrients, removing waste and maintaining temperature. It’s true that Muslims who observe a strict fast during Ramadan go without water while the sun is up. This is done as an act of self restraint and to show their faith in Allah.
If you are trying out IF for health purposes, rather than religious ones, it is advised to continue drinking water during your fast time. This is especially important in hotter months and if you are exercising. Since water on its own does not have any calories or sweeteners, it will not have an affect on the body’s glucose or lipid levels. You may also choose to enjoy other beverages such as lemon water, sparkling water, tea or coffee without added sugars, sweeteners or fats. If you’re fasting for medical reasons, talk to your doctor about beverages you can drink during your fast time.
All Methods of Intermittent Fasting Have the Same Effects
This is not completely true. Several studies have shown that a variety of fasting regimens can lead to health benefits like weight loss and improved blood glucose levels. One review of many studies found that the alternate day fasting method was the most effective in generating weight loss (5). This involves no calories consumed one day and a normal diet consumed on the following day.
Intermittent Fasting is Safe for Everyone
This one is certainly a myth. As with any new diet, it’s important to check with a doctor before trying something new. IF can be especially dangerous for people who are at risk for an eating disorder, or those who require a high caloric intake. This can include women who are pregnant or breast feeding, children and teens, people trying to gain weight or muscle, and many others. For most other people, IF is quite safe and has few risks or side affects. This is the case assuming the maximum fast time is 24 hours. There may be additional risks for a longer fast.
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