WHAT IS INTERMITTENT FASTING?
Intermittent fasting (IF) is all the rage right now, but a lack of understanding behind how it works is causing some to build some very unhealthy habits and relationships with food. So before you consider starting a fasting based program, lets learn about what fasting is, who should be using it and how it can be an effective strategy for you.
Let’s break IF down into its components to better understand what it means:
- Intermittent: occurring at irregular time based intervals
- Fasting: intentional abstinence or reduction from some or all food, drink, or both
So intermittent fasting can be defined as intentional reduction of food and/or drink for some time-based interval. If you want to be a snob, yeswe all technically practice some form of intermittent fasting. You could say that we fast between meals, even between bites of the same meal. But you’re not THAT person, right?!
HORMONES AND FASTING
Intermittent fasting works by causing changes in our endocrine system that affect our metabolism. Hormones like glucagon, leptin and insulin are primarily affected by fasting strategies. Intermittent fasting increases insulin sensitivity while decreasing the hunger hormone, ghrelin. As an added benefit, lowered ghrelin levels during a fast improves dopamine levels in the brain, improving cognitive function. (6) Fasting also lowers the insulin-to-glucagon ratio, which stimulates fat cells to release and break down fat to fuel different bodily functions. (2)
FLIPPING THE METABOLIC SWITCH
Fasting has a drastic effect on our metabolic system via glycogen depletion. Our bodies store glycogen in both our liver and our muscles, about 300 to 400 grams or so to be exact. When we burn through our liver glycogen stores, our bodies hit a tipping point better known as the metabolic switch where fatty acids are mobilized from our fat stores. This point usually occurs at the twelve-hour mark after the beginning of a fast. Although it is referred to as a switch, it's really more of a sliding spectrum where the majority of our fuel source comes from free fatty acids (1). The metabolic switch can vary for different individuals depending on pre-existing liver glycogen content at the beginning of the fast, and on the amount of the individual’s energy expenditure/exercise during the fast.
BENEFITS OF FASTING
Increased insulin sensitivity leads to more efficient nutrient partitioning, so the food that you eat goes further for you!
Improved cognitive function is a result of higher levels of dopamine and lowered neuro-inflammatory pathways known to cause cognitive decline. (5)
Increased autophagy is a result of adaptive cellular stress responses that cause a higher rate of damaged or dead cellular turnover that clears the path for healthy cell creation. (7)
Increased longevity can be directly linked to increases in human growth hormone which allows for preservation of lean muscle tissue as well as increased bone density.
Increased mitochondrial health leads to higher daily energy production as well as healthy aging of cells. (9)
Meal Mindfulness is the process of understanding your response to hunger. Fasting quickly acquaints you with what it feels like to be hungry versus eating based on your past eating cadence.
Fasting and Starving Yourself Are NOT The Same Thing!
When practicing intermittent fasting, you are not lowering your caloric intake, you are simply compressing the consumption of food to a shorter window of time. Caloric restriction has long been the go-to strategy for the triggering of biological pathways leading to improved cardiovascular, metabolic and mitochondrial health, yet intermittent fasting has quickly become a competing strategy due to its higher levels of sustainability (10).
Long term caloric restriction can lead to suppressed metabolic rates and hormonal imbalance, which as an extended strategy can cause you to eat less and less. Eventually you hit a point where your basal metabolic rate is so slow that you are eating the calories required for someone half your size, yet you still are gaining weight. In contrast, intermittent caloric restriction brings all the same benefits, without the harmful hormonal downstream effects.
The 16:8 Fast
16:8 fasting is the gold standard in basic fasting protocols. It is comprised of a daily 16 hour strict fasting window followed by an 8 hour feeding window. During the 16 hour fasting window, you are allowed to consume water, coffee or tea.
The Warrior Fast (20:4)
Warrior fasting is based on the dietary styles of warriors throughout history. It allows for 20 hours of highly restricted caloric intake (water, small amounts of protein and fat) followed by four hours of feasting.
5:2 Fasting is designed to allow people to live their normal lives 5 days a week, and then restrict daily calories to 500-600 two days a week.
Eat Stop Eat
Fasting is practiced every other day, 24 hours at a time. This advanced strategy should be practiced by someone who is well seasoned in other fasting protocols and should not be used as a beginner strategy.
Fat fasting allows for the intake of dietary fats like butter, MCT oil or coconut oil in combination with water, coffee or tea. The idea behind fat fasting is to mimic strict fasting by lowering the insulinogenic response to food. Your body doesn’t release insulin when fat is the only dietary intake. Fat fasting is an incredible strategy for fasting newbies, as it will allow you to stay full, yet enjoy a lot of the same benefits as a strict fast.
How To Harness the Benefits of Fasting Via Movement
As your liver glycogen is depleted and your metabolic switch flips, it’s a prime time to move underneath something called your anaerobic threshold. Your anaerobic threshold occurs at a specific heart rate in which your body switches its preferred energy source from fat to carbohydrate. Without getting too technical, think of it as the point at exercise induces breathing that would prevent you from having a conversation with someone next to you.
Planning movement in a fasted state under the anaerobic threshold harnesses the body’s hormonal cascade that mobilizes fat to be burned as fuel. As an addition, interjecting bouts of low-intensity activity (walking, biking, etc.) has been shown to increase insulin sensitivity and nutrient partitioning after meals. (3)
So how do we apply this? Do low intensity movement during your fasted state as well as after meals. Go on a walk when you wake up in the morning before you eat anything or after you eat a meal. A ten minute walk can change the way that your body partitions and utilizes the foods that you normally eat. A lot of people complain about not having time to exercise … everyone has 10 minutes, no excuses.
Fat Fueled Movement
As we discussed previously, the anaerobic threshold is the point at which the body begins to shift its preferred energy source from fat to glucose. When training, you want to intermix exercises that will take you in and out of your anaerobic zone.
Aerobic exercise: jogging, bike rides, yoga, walking, surfing
Anaerobic exercise: HIIT, sprinting, weight lifting
My favorite way to ensure that I am performing in the gym is fueling pre-workout with fats while ensuring that my glycogen stores are full. This usually takes the form of eating carbohydrates at night with my dinner, and then exercising in the morning after eating a package of Phat Fudge. The carbs at night ensure that my glycogen stores are topped off, so that when my workout breaks through my anaerobic threshold, I have the energy source that my body needs. The Phat Fudge provides the dietary fats required for aerobic work, while also providing me with a bit of caffeine for increased energy and fatty acid mobilization, adaptogenic maca root for increased internal energy production and cinnamon for stabilized insulin levels.
Try this protocol on for size:
Dinner: 1 Medium Roasted Sweet Potato, 4 oz Grass Fed Flank Steak + 1 Tablespoon of Chipotle Avocado Mayo Aioli (Calories: 451, Protein: 27, Carbs: 40, Fat: 21)
The following day: Fast until 1 hour before your workout, eat Phat Fudge and then workout
Working out Tomorrow? Refuel with: 2 Cod Fish Tacos w/ Cassava Flour Tortillas and ½ Avocado (Calories: 352, Protein: 25, Carbs: 30, Fat: 14)
Not working out Tomorrow? Pan Fried 4 oz Salmon, 3 cups of shredded kale/spinach, 2 tablespoons of Primal Kitchen Caesar dressing and 1 Tablespoon of Pumpkin Seeds (Calories: 356, Protein: 30, Carbs: 15, Fat: 22)
Dynamic Fasting: The Answer to the Question “Which Type of Fasting Is For Me?”
We are creatures of our environment and the paradigms that we define our actions with. Each of the above types of fasting represents a tool in our toolkit for tackling the adversity that life throws at us. Over the years, I have practiced all of the different types of fasting and have identified my special fasting sauce that I’d like to share with you.
For beginners, start with Fat Fasting and progress to the 16:8 or Warrior Fast a few days a week. Do this by swapping out your carb laden breakfast with a fat fueled breakfast. A package of Phat Fudge simplifies this process, whether you eat it straight or blend it into your morning coffee.
As you progress, start to think about your day at hand. What will you be doing and what is your intention? If you’re going to be hitting the gym and pushing really hard, maybe a 20 hour strict warrior fast isn’t your best option. Consider a modified 16:8, where you break your fast shortly after your exercise with a balanced meal to provide amino acids, replenish glycogen and balance insulin levels. If you’ve got a day of deep work requiring you to be cognitively on fire, consider a strict 16+ hour fast, followed by a fat fast to extend the benefits. This would mean subbing coffee or tea in the morning for breakfast, grabbing a pack of Phat Fudge when you first get hungry, and breaking your fast in in the mid to late afternoon.
Personally, I think of fasting as a cumulative process—how many hours a WEEK can I add up in the fasted state. I practice 16:8, Warrior, 5:2 and Fat Fasting every week based on my schedule and intention each and every day. I challenge you to consider how fasting may fit into your lifestyle.