What Is Fasting And How Does It Work
A good rule of thumb for those wanting to fast to improve their metabolic and overall health is to leave at least 12 hours between meals ideally more on a regular basis, according to Dr Adam Collins, Principal Teaching Fellow in Nutrition at the University of Surrey.
Time-restricted eating is often used for weight-loss, and some people increase the daily fasting period to 14 hours or 16 hours. There are other forms of intermittent fasting, including the 5:2 approach, which involves very restricted eating on two days of the week, with normal eating on the other five. The 4:3, or every other day, approach involves similar restrictions on alternate days. Whichever one you choose, make sure youre doing it consistently, Dr Collins advises.
A Better Night’s Sleep
If youve ever felt like you slipped into a food coma after a big meal, you know that diet can have an impact on wakefulness and sleepiness. Some IF followers report being able to sleep better as a result of following this way of eating. IF and mealtimes may have an impact on sleep, Rose-Francis says. Why?
One theory is that IF regulates circadian rhythm, which determines sleep patterns. A regulated circadian rhythm means youll fall asleep easily and wake up feeling refreshed, though research to support this theory is limited, Nature and Science of Sleep.
The other theory centers on the fact that having your last meal earlier in the evening means youll have digested the food by the time you hit the pillow. According to the National Sleep Foundation, digestion is best done when youre upright, and going to sleep with a full stomach can lead to bedtime acid reflux or heartburn, which can make it hard to fall asleep.
Intermittent Fasting Schedules To Follow
There are many ways to practice intermittent fasting for weight loss. The following are some of the most popular schedules:
Time-restricted eating: This involves consuming all of your meals within a period of 4-12 hours in a day. For example, you could choose to have your meals and calories between 8 am and 6 pm. Limiting your calorie intake to daylight hours is called eating with the sun. Time-restricted eating is particularly beneficial if you eat your meals before sunset. Not only does this help you eliminate bad habits like late-night snacking, but it improves your sleep and blood sugar control. Over time, time-restricted eating can lower your blood sugar levels, make you more sensitive to insulin, and reduce your blood pressure.
One-meal-a-day : This involves packing all of your days calories in a single meal that you consume within 1-2 hours. A small study conducted by Dr. Jason Fungs research group showed that fasting for 24 hours 3 times a week and eating only dinner on fasting days, eliminated the need for insulin in type-2 diabetic patients. This fasting approach also resulted in improved HbA1C, lower body mass index, and reduced waist circumference.
What intermittent fasting schedule is right for you? Find out here.
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What To Expect With Intermittent Fasting
- You will most likely notice your stomach is grumbling during fasting periods, primarily if you are used to constant grazing throughout the day.
- Fasting may also lead to an increase in the stress hormone, cortisol, which may lead to even more food cravings.
- Overeating and binge eating are two common side effects of intermittent fasting.
- Intermittent fasting is sometimes associated with dehydration because when you do not eat, sometimes you forget to drink. For good health, it is essential to actively stay hydrated throughout the day by drinking, on average, three liters of water.
- You will most likely feel tired because your body is running on less energy than usual, and since fasting can boost stress levels, it can also disrupt your sleep patterns. It is crucial to adopt a healthy, regular sleep pattern and stick to it so you can feel rested on an everyday basis.
- The same biochemistry that regulates mood also regulates appetite with nutrient consumption affecting the activity of neurotransmitters like dopamine and serotonin. Fasting could play a role in anxiety and depression.
- Deregulating your appetite may do the same to your mood and therefore you will most likely feel irritable on occasions when you are fasting.
Ways To Use This Information For Better Health
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Getting Started With If
If you use the IF method, you should still pay attention to what you eat. It is still important to get vitamins, proteins, minerals, fiber and hydration. IF creates a calorie deficit because you are limiting eating opportunities. Although that allows you to eat two larger meals that may be less healthy and tastier, while keeping a calorie deficit, your body still responds to what you put into it. So cleaner, healthier food is better than junk food.
If your main goal is health benefits and not loss of body fat or weight, counting calories is probably not necessary. As you move closer to your goal, make sure you are getting your macronutrients.
Theres an adjustment period when you start using an IF method and you may become lightheaded as your body adjusts to longer periods without food. If you feel an overwhelming need for food, or become nauseous or dizzy, eat or drink something.
Exercising is perfectly fine while fasting. If your main goal is to lose body fat, try working out at the end of your fast and right before your feeding window. Youll burn calories when your body is already primed to be using fat as a main source of fuel, and you sensitize your muscles to the protein and nutrients youre about to feed it. If youre an explosive athlete, however, try working out in the middle of the feeding window so youll have available carbohydrates in your system that are vital for performance.
Why 16 Hours For Intermittent Fasting
Since we know now that prolonged fasting burns fat more efficiently, why should we fast for 16 hours?
There are two substantial reasons for 16 hours of intermittent fasting:
- Integration into everyday life
- Induction of autophagy
On the one hand, the 16 hours of intermittent fasting have practical reasons. If you skip breakfast or dinner, you have already reached the 16 hours of intermittent fasting.
To eat only from noon to 8 PM can be easier than you might think because morning hunger can be unlearned.
Thus, and because it means that you can always have dinner with your family, you can comfortably integrate this 16/8 schedule into everyday life.
Autophagy, on the other hand, is the intracellular recycling system in your body and the second reason for the 16 hours of intermittent fasting.
Moreover, autophagys discovery was such a scientific milestone that it was rewarded with the Nobel Prize .
When food is scarce, the body goes from growth into maintenance mode. Then it does not want to grow any further but to recycle broken cell parts.
Therefore, the following three nutrient sensors exist in the body, switching autophagy on and off:
- Insulin: Sensitive to carbohydrates and proteins
- mTOR: Sensitive to proteins
- AMPK: Sensitive to lack of energy in cells
So if the dietary energy supply regardless of which macronutrient to cells is interrupted, cells want to react sustainably and use disused cell parts to generate energy.
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May Help Prevent Alzheimers Disease
Alzheimers disease is the worlds most common neurodegenerative disease.
Theres no cure currently available for Alzheimers, so preventing it from showing up in the first place is critical.
In a series of case reports, a lifestyle intervention that included daily short-term fasts was able to significantly improve Alzheimers symptoms in 9 out of 10 people .
However, more research in humans is needed.
Studies in animals suggest that intermittent fasting may be protective against neurodegenerative diseases such as Alzheimers disease.
Why Is If Better Than A Regular Diet
Depending on the diet, intermittent fasting may reduce the amount of muscle loss and avoid the decrease in metabolism thats often seen with longer-term calorie restriction . Nothing in particular says it is better, compared to any other. Its just another tool to try, and one that happens to be very effective.
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What Laura Martin Md Says
Most of the intermittent fasting diets recommend cutting back to 500-600 calories on fasting days. In general, for many people this would be medically safer and easier than not eating at all on those days.
Remember to drink enough on fasting days to prevent dehydration. And youll need to eat a healthy diet on days that you dont fast.
Who Should Try Intermittent Fasting
Intermittent fasting can be effective if you are interested in fat loss, changing your body composition or improving your overall health and reducing risks of diabetes, heart disease, etc. Because the concept and application are pretty simple, its also a good tool for those who have had a hard time adhering to other diets.
However, if you have uncontrolled blood sugar issues or a history of eating disorders, you are probably not an ideal candidate for intermittent fasting. Likewise, if you are an explosive or power athlete, your performance may suffer, depending on the timing of your workouts/competitions and your feeding window.
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Is It Good For Certain Conditions
If you have medical conditions, talk with your doctor before you try intermittent fasting.
Benefits To Gut Health
Short periods of fasting, such as skipping breakfast , may benefit your gut microbes, explains Professor Tim Spector of Kings College London in his book Spoon-Fed. Although research in the field is in its early stages, accumulating evidence suggests that during fasting, certain species of microbes replicate and feed off carbohydrates in the gut lining. This makes the gut barrier healthier and more efficient.
One explanation for this could be that gut microbes follow a circadian rhythm like you do. Microbe communities, like us, may also need to rest and recuperate as part of a daily circadian rhythm which could be important for our gut health, writes Spector.
Everyones body responds differently to skipping meals, so Spector suggests experimenting by giving breakfast or another meal a miss to see how you feel. Leaving a minimum of 12 hours between eating, even if its only occasionally, could improve your mood and energy levels in the short term , he argues.
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Your Digestive Function Improves
Are you giving your digestive system the rest it needs to do its job? If you’re eating frequently over the course of a 16- or 18-hour day, maybe not.
“Digestion is the most taxing system in our bodyit takes a lot of work!” says nutrition coach Megan Kober, RDN. “When you allow your digestive system to rest, your body can go to work on breaking down not only fat cells but also unwanted immune cells in the body.”
Because of the cell breakdown made possible by fasting, Kober says it’s the most efficient way to detox. Yes, even more than all those juice cleanses or pricey supplements that make questionable promises about removing “toxins.”
The Dos And Donts Of Intermittent Fasting
Humans have been fasting for many ages, mainly due to religious or cultural beliefs. However, in more modern times, it has proven to be valuable for health benefits as well! Here is a cheat sheet about intermittent fasting, and if it is the right plan for you.
What are the potential benefits for intermittent fasting?
Intermittent fasting can act as a reset button for your digestive system. By taking a break from eating, you are letting your body flush out excess insulin and allowing the liver to dispose of toxins. Studies have shown that intermittent fasting actually influences the gut microbiome microbes in the obese individuals actually had a higher rate of expenditure as far as for energy and storage. In addition, the gut microbiome is important in obese individuals due to the relation of systemic inflammation. Intermittent fasting provides an avenue to help burn visceral or deep fat, by allowing the body to use its own stored fat for energy versus consuming energy.
Which length of fasting is best for you?
The standard recommendations of fasting would either be a 12:12 fasting, meaning fast for 12 hours and eat for 12 hours. For example, eating is allowed between the hours of 8 am to 6 pm only.
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Can Reduce Insulin Resistance Lowering Your Risk For Type 2 Diabetes
Type 2 diabetes has become a very common diagnosis in recent decades.
Its main feature is high blood sugar levels in the context of insulin resistance.
Anything that reduces insulin resistance should help lower blood sugar levels and protect against type 2 diabetes.
Interestingly, intermittent fasting has been shown to have major benefits for insulin resistance and to lead to an impressive reduction in blood sugar levels .
In human studies on intermittent fasting, fasting blood sugar has been reduced by 36% over the course of 812 weeks in people with prediabetes. Fasting insulin has been reduced by 2031% .
One study in mice with diabetes also showed that intermittent fasting improved survival rates and protected against diabetic retinopathy. Diabetic retinopathy is a complication that can lead to blindness .
What this implies is that intermittent fasting may be highly protective for people who are at risk for developing type 2 diabetes.
However, there may be some differences between the sexes. One 2005 study in women showed that blood sugar management actually worsened after a 22-day long intermittent fasting protocol (
Intermittent fasting can reduce insulin resistance and lower blood sugar levels, at least in men.
Keeps Cells Healthy And Vibrant
When we fast we give our body time to rest and repair, tending to natural processes put in place to keep our cells healthy. Autophagy is an example of a process our body naturally undergoes to keep our cells healthy and in turn, keep us healthy!
Autophagy is the process our cells go through to remove waste and dysfunctional cells to help our body clean out damaged cells and regenerate new and healthier cells. Evidence suggests when we intermittent fast, we increase the frequency of this process, so our body works harder to remove any unwanted junk and dysfunctioning cells .
Increased autophagy may play a role in protecting us from several diseases including neurodegenerative diseases, cancer, inflammatory diseases, and cardiovascular diseases .
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The Dangers Of Intermittent Fasting
Intermittent fasting is a predetermined period where an individual purposely doesnt eat food. From a 12-hour fast to alternate day fasting, many kinds of intermittent fasting diets are becoming increasingly popular. Health professionals argue that intermittent fasting is not necessarily dangerous, but many also agree that intermittent fasting is not safe for everyone.
What Are The Possible Side Effects
There can be a number of possible side effects of intermittent fasting.40 Heres what to do if you encounter them:
- Hunger is the most common side effect of intermittent fasting. This may be less of an issue if youre already on a keto or low-carb, higher-fat diet.41Learn more
- Constipation is common. Less going in means less going out. However, keep in mind this is a normal response to eating less. It is not a concern and shouldnt require treatment unless you experience significant bloating or abdominal discomfort. Standard laxatives or magnesium supplements can be used, if needed.
- Headaches are common and tend to disappear after the first few times on fasts.42 Taking some extra salt often helps mitigate such headaches.43
- Mineral water may help if your stomach tends to gurgle.
- Other possible side effects include dizziness, heartburn and muscle cramps. Learn more
A more serious side effect is the refeeding syndrome. Fortunately, this is rare and generally only happens with extended fasts when one is undernourished.44
Since most of these side effects are manageable, they do not mean you have to stop your fast. However, if you truly feel unwell, are excessively dizzy, profoundly weak or have other severe symptoms, then you should break your fast.
Just remember to go slowly when you break it and prioritize fluids and salt . And of course, if the symptoms persist, see your doctor immediately.
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Intermittent Fasting Tips Tricksand Warnings
As you would before starting any new diet, speak with your healthcare provider for guidance. They can help you decide whether IF is the right plan for you, and give you a heads up about potential pitfalls and health hazards. Let your HCP know if youre on medications, as well, since IF can mess with them.
If you go ahead and try IF, experts recommend starting slowly and working your way up to longer periods without food. Some people may experience side effects like headaches, lightheadedness or mood changes at first, but fans claim they should disappear as you get used to it.
Remember to stay hydrated during your fast, Dr. Ergin says, since people who eliminate meals may neglect drinking water, as well. That can lead to dehydration and kidney problems, especially in patients already having baseline kidney problems.
Also keep in mind you should follow a nutritious eating plan for times you arent fasting. Emphasize wholesome foods like produce, lean protein, legumes, whole grains and good-for-you fats. Try to avoid binging on junk food when a fasting period ends. When you overeat, you are actually harming yourself more than youre helping yourself, Dr. Ergin says.
Be aware: Though IF is likely safe for most of us in the short term, ditching meals and drastically slashing calorie intake can be harmful to some, including: