What is Intermittent Fasting?
Intermittent fasting is an old secret of health. It has been practiced throughout human history and is a powerful health habit. Intermittent fasting is the practice of giving your digestion a longer time to rest in a 24-hour cycle than you usually do, and is actually the most natural possible rhythm for human digestion.
Modern life in western countries allows us to eat from the moment we wake up until the moment we go to bed. Big breakfasts and midnight snacks have become the norm. Food is always ready to grab! Yet overeating is a major cause of disease, inflammation, and even sometimes just plain old discomfort!
But now many people are re-discovering this dietary intervention. It can carry huge benefits if it is done right: weight loss, increased energy, reversal of type 2 diabetes and many other things. Plus, you’ll save time and money.
Is it the same as Starving Myself?
Fasting is merely the absence of eating for a period, and must not be confused with starving oneself. When you practice intermittent fasting you are still aiming to nourish yourself adequately each day, or if you are doing longer fasts, to balance healthy nutrition over the course of a week.
In many ways, Intermittent fasting is an extension of what we do naturally when we sleep. Any time that you are not eating, you are fasting. For example, you may fast between dinner and breakfast the next day, a period of approximately 12-14 hours. In that sense, fasting should be considered a part of everyday life.
The body only really exists in two states – the fed (insulin high) state and the fasted (insulin low) state. Either we are storing food energy, or we are burning it.
Insulin rises when we eat, helping to store the excess energy in two separate ways. Sugars can be linked into long chains, called glycogen and then stored in the liver. There is, however, limited storage space; and once that is reached, the liver starts to turn the excess glucose into fat. Some of this newly created fat is stored in the liver, but most of it is exported to other fat deposits in the body. While this is a more complicated process, there is no limit to the amount of fat that can be created. So, two complementary food energy storage systems exist in our bodies. One is easily accessible but with limited storage space (glycogen), and the other is more difficult to access but has unlimited storage space (body fat).
The process goes in reverse when we do not eat (fasting). Insulin levels fall, signalling the body to start burning stored energy as no more is coming through food. Blood glucose falls, so the body must now pull glucose out of storage to burn for energy. Glycogen is the most easily accessible energy source. It is broken down into glucose molecules to provide energy for the other cells. This can provide enough energy to power the body for 24-36 hours. After that, the body will start breaking down fat for energy.
Fasting allows the body to burn off excess body fat. This is normal and humans have fasted throughout history without detrimental health consequences. Body fat is merely food energy that has been stored away. If you don’t eat, your body will simply “eat” its own fat for energy
Intermittent fasting is not a diet but an eating pattern.
It involves missing certain meals on purpose with the result that you consume your calories during a specific window of the day, and choose not to eat food for a larger window of time.
Your digestive system wasn’t meant to be switched on all the time. The human body has a natural period when we are meant to rest and digest – allowing our parasympathetic nervous system to heal and our bodies to dump all of the metabolic waste we’ve accumulated throughout the day.
An ‘off’ period of 10-14 hours has been shown to reduce inflammation. It allows the body to draw energy from fat cells, giving the benefits of very mild ketosis and promotes the conversion of unhealthy white fat into more healthy brown fat.
It also has numerous other health benefits
- stronger insulin sensitivity and increased growth hormone secretion, two keys for weight loss and muscle gain.
- improved asthma-related symptom
- improved bio-markers for a host of chronic conditions (including diabetes, breast cancer, and cardiovascular disease)
- weight loss
- improved cognitive function
- It can level up your brain, including positively counteracting conditions like Parkinson’s, Alzheimer’s, and dementia.
Does intermittent fasting work by restricting calories?
By skipping meals you will generally eat less over the course of a day, and if done properly, intermittent fasting naturally cuts calories by about 25% daily. A recent study showed that both calorie-restricted dieters and intermittent fasters lost similar amounts of weight over a year period. However, that doesn’t tell the full story, as we already know that not all calories are created equal and that the timing of meals can also influence how your body reacts.
When you eat, your body spends a few hours processing that food, burning what it can from what you just consumed. Because it has all of this readily available, your body will choose to use that as energy rather than the fat you have stored. This is especially true if you just consumed carbohydrates/ sugar.
During the “fasted state” (the hours in which your body is not consuming or digesting any food) your body doesn’t have a recently consumed meal to use as energy, so it is more likely to pull from the fat stored in your body as it’s the only energy source readily available, hence burning fat.
The same goes for working out in a “fasted” state. Without a ready supply of glucose and glycogen to pull from (which has been depleted over the course of your fasted state, and hasn’t yet been replenished with a pre-workout meal), your body is forced to adapt and pull from the only source of energy available to it: the fat stored in your cells.
How do I do it?
Intermittent fasting also isn’t about restricting specific foods though those who promote it generally recommend a diet that consists of healthy, whole foods. It’s important that what you do eat still provides you with all the nutrients, vitamins and minerals that you need in a day
However Intermittent fasting is more about food timing. The difference between Intermittent fasting and other weight loss methods is not so much what you eat but when you eat, and when you don’t eat. The benefits of intermittent fasting come from the 10-12 (or more) hours when we don’t eat anything,
Examples of Different Intermittent Fasting Schedules
If you’re considering giving fasting a shot, there are a few different options for working it into your lifestyle.
Daily Intermittent Fasting
The Leangains Model of intermittent fasting uses a 16–hour fast followed by an 8–hour eating period each day. It doesn’t matter when you start your 8–hour eating period. You can start at 8am and stop at 4pm. Or you start at 2pm and stop at 10pm. Do whatever works for you and fits in with your lifestyle and family. If you feel like 16 hours of fast is too much, you can start with 12 hours of fast and build it up slowly until you get to a fasting time that you are comfortable with and which is having the effects that you desire.
Because daily intermittent fasting is done every day it becomes very easy to get into the habit of eating on this schedule. Right now, you’re probably eating around the same time every day without thinking about it. Well, with daily intermittent fasting it’s the same thing, you just learn to not eat at certain times, which is remarkably easy.
Alternate Day Intermittent Fasting
Alternate day intermittent fasting incorporates longer fasting periods on alternating days throughout the week.
For example, in the graphic below you would eat dinner on Monday night and then not eat again until Tuesday evening. On Wednesday, however, you would eat all day and then start the 24–hour fasting cycle again after dinner on Wednesday evening. This allows you to get long fast periods on a consistent basis while also eating at least one meal every day of the week.
The benefit of alternate day intermittent fasting is that it gives you longer time in the fasted state than the Leangains style of fasting. Hypothetically, this would increase the benefits of fasting.
Weekly Intermittent Fasting
One of the best ways to get started with intermittent fasting is to do it once per week or once per month. The occasional fast has been shown to lead to many of the benefits of fasting , so even if you don’t use it to cut down on calories consistently there are still many other health benefits of fasting.
What are the downsides to Fasting?
The biggest concern most people have is that Intermittent Fasting will lead to lower energy and a ‘hungry’ feeling during the fasting period that will ruin them. You may be concerned that you will spend all morning being miserable because you haven’t consumed any food, and thus will be miserable and ineffective at work.
Yes, the initial transition from EATING ALL THE TIME, to intermittent fasting MIGHT be a bit of a jolt to your system. However, once you get through the transition after a few days, the body will adapt and learn to function just as well only eating a few times a day. Once you retrain your body to NOT expect food all day every day (or first thing in the morning), these side-effects become less of an issue. In addition, ghrelin (a hormone that makes you hungry), is actually lowest in the mornings and decreases after a few hours of not eating too. The hunger pains will naturally pass!
AN IMPORTANT CAVEAT: Intermittent Fasting can be more complex for people who have issues with blood sugar regulation, suffer from hypoglycemia, have diabetes, etc. If you fit into this category, check with your doctor or dietitian before adjusting your eating schedule
If you would like to discuss with me whether Intermittent Fasting would work well alongside your current lifestyle and exercise regime, then please mention it at your next appointment with me.
Rachel Law is a personal fitness trainer based in New Malden, Surrey. Qualifications: ActivIQ Level 3 Personal Training; Burrell Education Pregnancy Exercise Prescription; Burrell Education Advanced Pregnancy Wellness Practitioner; Burrell Education Advanced Post Natal Exercise Prescription; Burrell Education 3rd Age Women Optimal Health and Nutrition; Burrell Education Peri Natal Athlete; Burrell Education Pelvic Flow and Freedom; Olympic Weight Lifting; Premier Global Kettlebells; FIE Level Assessment and Mentoring