Three Types of Intermittent Fasting 

Intermittent Fasting (IF) can be implemented regardless of what type of diet or eating schedule you are currently on. It works remarkably well with any schedule, especially if you are busy! There are actually three types of IF, as defined by Patterson et.al. in the Journal of the Academy of Nutrition and Dietetics.  

1. Alternate Day Fasting is the rotation of days in which no energy-containing foods or drinks are consumed with days where normal intake is consumed. Varady and Hellerstein have shown that in animals, alternate day fasting reduces total plasma cholesterol and triglyceride concentrations, and lowered cancer risk factors.  

2. Modified Fasting Regimens permit the consumption of 20-25% of energy needs on fasting days. Your “fasting” days are really just days of limited energy intake. Generally this regimen will be coincide with the 5:2 diet, where you have two days of limited energy fasting and 5 days of normal eating.  

3. Time-Restricted Feeding generally involves a daily fasting schedule in which 12-20 hours is devoted to zero energy consumption. For example if you fasted for 16 hours, that would leave you with 8 hours to consume energy. This is the type of fasting I will be focusing on, mostly because it is very adaptable and easy to modify to existing diets and schedules. Two applicable human studies have been done on Time-restricted feeding IF, Carlson et. al. and LeCheminant et.al. both found statistically significant weight losses in their subjects.      

How to Implement IF into your routine   

I personally have over 1 year of experience on the Time-Restricted Feeding regimen. I have seen my body fat percentage drop 5%, weight loss of 15 pounds, and all while experiencing significant strength increases. As a cyclist that translates into a higher Strength:weight ratio! As somebody just trying to lose weight translates into loss of fat + increase of lean muscle mass! Not to mention I’ve been experiencing less brain fog, improved memory and word recall, and increased motivation to get things done. Politt E. et. al. has demonstrated that short term fasting (IF) has an adverse effect on children’s late morning problem-solving performance. 

So why have I been experiencing increased cognitive ability and researchers have been finding the opposite? Ketosis, that’s why! I have also been employing a low carb, high fat diet to complement my intermittent fasting schedule. A ketogenic diet raises your blood ketone levels to past .48mmol/L, which is when your hunger hormones get reset! And rather than needing carbs to run, your body runs on fat which eliminates your insulin response. BUT, Instead of digressing and moving on to Ketosis and ketogenic diet, I will save that for my next post.  

To properly implement the time restricted feeding IF into your schedule, you will want to determine what your circadian schedule is. For instance, if you work days you may want to skip breakfast and not eat until later in the day, so a fast from 8pm-12pm might be a good fit for you. If you would rather eat earlier you can adjust your fasting schedule from 4pm-8am. It can literally be adapted to whatever type of schedule works best for your current situation! Currently I am on a 10pm-2pm schedule that allows me to start eating at 2pm.          

Common Nuisances While Fasting – HANGER!!   

Hanger is defined by the urban dictionary as a lethal combination of hunger and anger, the result of waiting so long to eat that your blood sugar drops to dangerously low levels, impairing both your mood and judgement. Believe it or not there is some science behind hanger, and it mostly involves hormones! Ghrelin is a hormone that your digestive system releases when it wants nutrients, it signals your brain that it is time to start eating. Our bodies produce massive amounts of ghrelin when we are about 14 hours into a fast. The antagonist hormone to ghrelin is called cholecystokinin (CCK). When our bodies release this it makes us feel full. A study done by Chearskul S et. al. concluded that injecting people with CCK mid meal caused them to stop eating. These are two very powerful hormones that have profound effects on our ability to adhere to a fasting schedule, but only indirectly contribute to Hanger. Two more important hormones need to step in to initiate the full on hanger rage we all know too well. Sensing the lack of fuel, our bodies will secrete adrenaline and cortisol to commence the raising of insulin and ultimately blood sugar. The good news: all of these hormonal responses can be completely avoided by raising our ketone levels!    

Fasting and Ketosis   

You may have heard of something called the ketogenic diet. This is basically low carb, high fat energy intake, making your body adapt to using fat as its primary fuel source. By dipping slightly into ketosis, we can effectively “reset” our hunger hormones and ultimately avoid the cascade of adrenaline, cortisol, and insulin. I will go further into the science and benefits of ketosis and ketogenic diets in my next post, as I could go on for days!    

Thanks for reading Part 2 of Intermittent Fasting: Scientific Evidence for Benefits of Fasting and How to do it RIGHT.

Part 1 can be found here.    

Your friend in health, Ryan.