Intermittent Fasting
Is Intermittent Fasting a Dietary Trend or a Long Term Solution?
In popular culture dietary recommendations can shift radically from month to the next - to be honest even as someone who is up to date on the latest nutritional research, these trends can leave my mind spinning. For example, the saturated fat debate - one group explains that saturated fats are excellent and another group demonizes them. Well, it all starts with the fact that most of the nutritional science research is observational studies meaning it is typically a correlation based study. Meaning that eating x is related to y. Eventually what happens is someone gets ahold of these studies publishes a book regarding the research findings, media picks it up and overnight that food is a "Superfood" or the dietary recommendations are a fix for x, y and z. Additionally, I believe it is worth noting that when it comes to nutritional research there is often a relationship between diet and behavior and this is where observational studies can be problematic. This is due to the fact that those individuals who typically eat a healthy diet are more likely to engage in healthy behavior, whereas those who typically eat unhealthy are more likely to engage in behaviors that are considered unhealthy (i.e. sedentary lifestyle, poor sleep behavior, etc) thus increasing risk for chronic disease such as obesity, type 2 diabetes, heart disease and more.
This blog is to going to be on focused on following:
1) What is an intermittent fast
2) Most manageable type of intermittent fast to achieve daily
3) The potential benefits of an intermittent fast for human health
Additionally there are a few topics I'd like you to bear in mind regarding intermittent fasting.
1) As modern humans we have access to food 24/7 thus we no longer have periods scarcity. Therefore, IF can be a substitute for the lack of abundance and scarcity found during our ancestors times.
2) IF does not necessarily lead to weight loss but sometimes losing weight can a byproduct of intermittent fasting. This is due to a shorter eating window, which typically makes it more difficult to overeat. Additionally, IF allows an individual to unlock the powers of lipolysis (commonly known as the ability to burn fat).
3) Pregnant women should never IF. This is due to the fact we do not not the body to believe it is a time of scarcity while creating a human life. Additionally, there are a number of others that should not follow an IF without medical supervision such as those with a history of eating disorders. ( It's important to note that everyone should talk to their healthcare provider before beginning to IF, to ensure IF is right for you)
4) There are a variety of ways to IF - this blog is going to be focused on time restricted eating.
5) There is some debate as to what allows you to remain in a fasted state. Some believe it's water only, whereas others believe water, tea and coffee all met the criteria. In short it comes down to what the goals of the fast are - in some cases as long as the caloric load is less than 50 calories you will remain in a fasted state.
What is Intermittent Fasting?
Intermittent fasting (IF) in the simplest of terms is eating within a specific window of time followed by a period of fasting. IF can be broken down into two categories; time restricted eating and calorie restricted eating. This blog is going to be focused primarily on time restricted eating due to the fact it is the one I'm most familiar with within my personal life. Additionally, time restricted is typically easier and more likely to be adhered to due to lack of complexity. On the other hand caloric restricted fasting such as a the 5:2 requires more planning as one eating normally for 5 consecutive days followed by 2 days of caloric restriction (CR) (typically 500 - 600 calories). At this time this blog is being written, CR research is largely focused in longevity - with most scientific literature demonstrating that CR can increase lifespan, improve insulin sensitivity and more. Therefore, if longevity and increasing lifespan is of interest to you, you should look at David Sinclair's work.
Since we are focusing on time restricted eating, let's discuss how this type of IF would look. Time restricted is broken down into two parts, which both parts being expressed in number of hours per day. These 2 parts can be thought of as the eating window and the fasting window. During the eating window, you are allowed to consume food as you normally would. During the fasting window you continue to consume water and/or tea and coffee. And if you recall from earlier some individuals will even consume foods that are less than 50 calories i.e. Essential amino acids before and/or during and/or after a workout (especially if muscle growth/repair is important to the individual.
The easiest time restricted eating to begin with is the 12:12. Meaning a 12 hour fast and 12 hour eating window. The most common is 16:8 - which is fasting for 16 hours and an eating window of 8 hours. Additionally there is a 24 hour fast which individuals sometimes implement once a month or quarter to help "clean things up". It's important to point out that an individual may never progress from a 12:12 and that is perfectly OK. Next we are going to discuss how 24/7 access to food can impact human physiology and bioenergetics.
24/7 Access to Food
Hunting, gathering and growing your own food in today's modern world is not necessary to obtain calories. However, this also means calories are easy to come by and periods of scarcity is not common. Without diving too deep into bioenergetics, I'm going to attempt to explain how abundance and scarcity impacts the human body.
Periods of abundance would also be known as anabolism, meaning to build up or create. During anabolic states, a couple things are happening. First, the storage of energy with anabolic hormones such as insulin, growth hormone, etc. The human body starts by storing glucose as glycogen within the muscles and liver, if too much is consumed (meaning too many calories) then this energy gets stored as fat through a process called lipogenesis.
Second, during an anabolic state the body builds and repairs muscle tissue. This is why individuals who want to put on muscle mass perform anabolic exercises such as deadlift, squat, etc and typically consume a high quality protein + smaller quantities of carbohydrate post-workout. It's important to point out this is the simplified version of what's occurring during an anabolic state, the body is performing an array of tasks to repair the body to ensure it's stronger for the next day.
On the other hand, periods of scarcity would be known as catabolism, meaning to break down. Catabolic states can occur for a number of reasons such as, during aerobic activities, fasting periods and/or lack of recovery or sleep. The hormones adrenaline, cortisol and glucagon are released during a catabolic state to assist with turning glycogen to glucose (energy) and burn fat through a process called lipolysis. During a catabolic state, you're breaking down body fat and muscle which can lead to an overall decrease in mass, body fat and muscle mass.
I introduced the basics of anabolic and catabolic states to explain how 24/7 access to food could impact the bioenergetics of the human body. If an individual is in a regularly fed state, meaning eating every couple hours for 12-16 hours of the day, they are mostly in an anabolic state (See example 1) Whereas if an individual eats within a smaller window, they aren't in a regularly fed state and thus have the opportunity to achieve some level of a catabolic state, these fasting days can be anywhere from 12 hours up to multiple days (See example 2)
Example 1
Jane recently started a new job and it requires her to wake up at 4:30am. Since she doesn't want to miss out on breakfast, she eats her first meal at 5:30, she snacks every 1-2 hours until lunch at noon, after lunch she snacks again every 2-3 hours until her dinner at 7:30pm, she then sits down to watch her favorite show and snacks on popcorn until she heads to bed at 9pm. In this example, Jane was pretty much in an anabolic state the whole time she was wake, totaling a 15.5 hour eating window, with 8.5 hours of catabolic time. Actually this isn't exactly true because it takes approximately 2-3 hours for the bioenergetic effects of a meal to "wear off". Meaning she's actually catabolic for closer to 5.5-6.5 hours each day.
Example 2
Bob's wife, Gretchen, recently started eating within a 12 hour window, also known as a 12:12 intermittent fast. Since he wanted to eat meals with his wife, he decided he too was going to eat within a 12 hour window. Bob and Gretchen eat their first meal at 7am and finish their last meal by 7pm, with little to no snacking between meals. In this example, Bob and Gretchen's eating window is 12 hours with 12 hours of catabolic time, however remember this is likely closer to 9-10 hours due to the bioenergetic effects of a meal to "wear off".
While the difference between a few hours might not sound like much, there are several differences.
1) Fasting for 12 or more hours increases the rate of fat oxidation which means it improves the ability of the body to burn fat.
2) Fasting can increase energy, due release of adrenaline, which makes sense because more energy would allow an individual a greater chance to find food, which would help them to survive.
Additionally shorter eating windows have benefits for the gut, hunger hormones (ghrelin and leptin), brain, heart and longevity to name a few.
Should I Skip Breakfast While Intermittent Fasting?
During the 1960's nutritionist Adelle Davis famously stated: “Eat breakfast like a king, lunch like a prince and dinner like a pauper.” (1) Today there are many studies that demonstrate that omission of breakfast can lead to an increased risk of disease such as type 2 diabetes. However, these are largely observational studies which have their flaws. Therefore, it is largely a matter of preference when it comes to breakfast timing. At some point you will eventually be "breaking your fast", at what time of the day you do so is not as important as ensuring you are consuming healthy foods throughout the whole day. Below I've provided three examples of IF, specifically time restricted eating that I typically engage in.
Example 1 - I am currently following a 12:12 and start eating around 7am and end at 7pm.
Example 2 - Last year I was on a 16:8 and was started eating at 9:30am and ended at 5:30pm
Example 3 - Occasionally, I would do a 24 hour fast stopping at dinner and start eating during dinner of the following night.
I've also provided a fourth example of using amino acids and creatine before a "workout" and why I believe they allow me to maintain a fasted state.
Example 4 - I often surf at dawn and consume essential amino acids and creatine on the drive to the break, I've taken my resting blood glucose before and after and have never noticed an increase in blood glucose. Therefore, I have no reason to believe an non-insulinogenic supplement or food such as essential amino acids would have an deltrious effect on the glycemic impact of fasting. However, if you are fasting for autophagy there could be a reduction in autophagy, which is when your body undergoes cellular "waste" clean up.
Does Intermittent Fasting Mean Weight Loss?
Not necessarily. Weight loss occurs primarily through respiration, specifically exhaled Co2, more specifically carbon of the carbon dioxide. However, IF could lead to body composition changes, this is likely due to the fact shorter eating windows increase the likelihood that your body will burn fat (lipolysis). (Remember that insulin and lipolysis are basically inversely related - meaning eating increases insulin which decreases lipolysis. Whereas not eating increases lipolysis and decreasing insulin). In an ideal situation the more time spent in lipolysis equals more time exhaling fat. However, individuals need to take into account food consumption. As too much food even in a restricted time frame will likely result in weight gain. Therefore, IF is only one piece of the puzzle when it comes to weight loss. For weight loss to occur carbon needs to be released from the body. The simplest way to do this is to increase respiration rate (RR) during movement and/or exercise. By moving regularly the body will increase RR which means more Co2 being blown off, which means an increased potential for weight to lost. It's important to note, that this is a simplified version of weight loss. I felt it was important to mention as often times dietary changes are the only change individuals implement when trying to lose weight.
Recap of Intermittent Fasting
Over the past couple years intermittent fasting has gained in popularity, however is still not mainstream within the "dietary trends". Time restricted eating is a type of IF that is most commonly followed as it does not require calorie counting. Fasting periods can vary from 12 hours to several days depending on the outcomes of the fast. With the most common period of 16 hours. IF does not necessarily mean weight loss as weight loss occurs through the exhalation of Co2. Our ancestors would have had periods of scarcity which would have allowed them to "tap into" lipolysis, Today, IF can act substitute for the lack of scarcity found in the modern human diet. Therefore, with this all being said, I believe intermittent fasting is a long term solution, that most individuals should try to implement in some way shape or form. Lastly, it’s important to remember to always talk to your health care provider to ensure that IF would be suitable for your unique health.
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References:
1) Sifferlin, A. "When to eat breakfast, lunch and dinner." Time(2013).
