Intermittent Fasting
What is intermittent Fasting?
Intermittent fasting rearranges your eating schedule to allow your body to go anywhere from 12 to 18 hours without food throughout the day.
Typically, people eat anywhere from three to five times per day, that is generally three meals and a couple snacks. When doing intermittent fasting however, regimented meal times are no longer rule your way of eating, and the “fasting window” between meals is extended. For example, a person who eats breakfast around 7-8am, lunch around 12-1pm and dinner around 5-6pm (with snacks in between) would stop eating after dinner (6pm). They’d then break their fast anywhere from 8am-10am depending on the length of their fasting window.
For most people doing intermittent fasting, the fasting window extends to about 14-16 hours — roughly three times as long as people who don’t fast. However, there are no strict times on intermittent fasting so the length will vary from person to person.
How does it work?
When your body is in the fed state, it operates differently to when it’s in the fasted state. That is, after you’ve consumed a meal, your body will absorb and metabolize what you’ve ingested in order to convert it to a readily available source of energy (ATP) capable of fueling your cells. This business of turning food into ATP is actually pretty costly in terms of energy! This is why you may hear people refer to the ‘rest and digest’ state and why people prefer to exercise on an empty stomach so that energy is directed to their muscles rather than their digestive system.
When you’re in a fasted state there is no ‘incoming energy’ to draw on. In this case, your body must draw from another pool — stored energy, also known as fat stores. When there is no circulating glucose to provide an immediate source of fuel, the body taps into stored glucose, found in the liver as glycogen. This happens before you tap into stored body fat located in fat tissue all throughout the body. If you’re following a strict ketogenic diet, however, liver glycogen stores will be lower than when on a standard diet, so you can tap into body fat stores more quickly and intensively. This ‘forced’ reliance on body fat is characteristic of both intermittent fasting and keto, making them excellent fat-loss tools. People on a ketogenic tend to feel like they’re appetite is improved and that they no longer crave a third meal. This naturally puts you into a pattern of intermittent fasting.
Furthermore, during the fasting window we are doing two interesting things. First, we’re not taking in any calories for a specified period of time and thus forcing our bodies to rely much more on fat and less on glucose (carbs). We still get all the glucose we need from our bodies making it for us, through the process of gluconeogenesis (creating glucose from protein and fat). It’s a much more fine tuned way of regulating our blood glucose than by relying on eating fast-absorbing dietary carbs. Secondly, we extended the fasting window that is too short, now more fully benefitting from a process called autophagy. This ‘cleans out’ the body — i.e. gets rid of old, damaged or worn-out cells and structures which would otherwise accumulate and damage us. Think of it as your body recycling some of these parts to make room for new, younger better functioning ones.
Different ways to Intermittent Fast
The 16/8 Method
This method restricts the eating window to a period of 8 hours and extends the fasting window to 16 hours each day. For some, the fasting window can range from 16-20 hours, further restricting the eating window.
Breakfast n’ Dinner
This pattern of eating is a great way to free up some time. For example, it could mean having a 6-7am breakfast and an 8-9pm dinner. It even gives you time for a quick workout after work, before sitting down for dinner.
Alternate Day Fasting
It involves rotating between eating the classical 3 meals a day and fasting for the whole day on others. For example, eat normally Monday, Tuesday, Wednesday, Friday, and Sunday, but fast the whole day Thursday, and Saturday.
24 Hour - One Meal a Day
The 24-hour fasting or One Meal A Day method is simply having one meal every 24-hours. For example, eating dinner at 7pm and not eating again until 7pm the following day.
In order to thrive with intermittent fasting, the following things are necessary:
Adequate protein intake (1gm/pound of ideal body weight).
Strength Training
Movement
Proper sleep (7-8hrs/night) without exception; there are far too many benefits from high quality sleep, including secretion of HGH and benefits from the glymphatic system that is only available at night. Also, blood sugar regulation is correlated with proper sleep.
Stress management
Does IF help with weight loss? What are the other benefits?
Not only does intermittent fasting reduce your feeding window such that you’re likely lower your excessive calorie intake, but you’re also forcing your body to tap into fat stores. Tapping more fully into fat stores carries additional metabolic benefit, on top of the obvious reduction in fat stores.
Calorie restriction independent benefits. Intermittent fasting is most probably the eating frequency our biology is most comfortable with. A study looked at alternate day fasting (a kind of intermittent fasting) found that insulin levels and measures of insulin resistance were more improved in the alternate day fasting group compared to the classically calorie restricted group who ate the same amount of calories.
Weight-loss independent benefits. Intermittent fasting isn’t just about losing fat but also about feeling better and having better blood markers which can predict disease risk. One study found that cardiometabolic markers improved in the early time-restricted feeding group (a kind of intermittent fasting) who ate within a smaller eating window (6 hours) compared to other one eating within a more extended window (12 hours).
Improves glucose uptake efficiency and insulin sensitivity. Intermittent fasting helps to increase insulin mediated glucose uptake rates into tissues that are able to use it for fuel, for example muscle. It also helps to optimize the levels of certain biomarkers that are associated with chronic diseases, like insulin and glucose. Fat fasting is also a great way to improve insulin sensitivity, as well as deepen the extent of ketosis if you have also chosen to follow the ketogenic diet.
Normalizes/decreases appetite. When your body is running off of your main energy store, body fat, rather than frequently incoming fast-absorbing carbs, your body is using a stable and well regulated supply of energy. Intermittent fasting has been shown to help people eat less in the evening, as well. As the day proceeds, our metabolic responses to incoming food aren’t as favorable compared to earlier in the day. As such, it may therefore be healthier to increase food consumption during the day when our bodies can metabolize and use energy more efficiently.
Improves athletic performance. While it may not seem like a method of ‘weight loss,’ it’s obvious that an improved ability to exercise contributes to an improved body composition in terms of muscle-to-fat ratios and general health status (especially mental health). Indirectly, these benefits in other areas of lifestyle could help improve weight-loss goals (e.g. better sleep). Studies have shown that working out in a fasted state leads to better metabolic adaptations (increased training stimulus) and improved metabolic responses to post-workout meals, which are critical for recovery. With that said, when our bodies are able to be more efficient during workouts and recovery, we can train better, harder, and see more improvements in body composition.
