Introduction to Intermittent Fasting- with Dr. Colin Race, ND


Note- this information comes from Dr. Race and is reproduced with permission. Dr. Race and his wife own a natural health clinic in NW Calgary and can be found here. If you have any questions please reach out to the clinic, ask an Amaranth Wellness staff, or consult your medical professional of choice.



What we eat and how we eat have a profound effect on our bodies. Most common diseases and ailments can be addressed through healthy lifestyle and diet choices. Beyond simply preventing issues, lifestyle habits like intermittent fasting can be a powerful tool in achieving a healthy body weight, becoming metabolically flexible (burning both fat and sugar as fuel), balancing insulin and blood sugar, and increasing energy and improving mental clarity.

Start with a blank canvas when it comes to fasting, there are many myths and preconceived ideas out there. Yes, fasting can be very beneficial for most people, no it will not lower your metabolism or starve you, yes it can be one of the most straightforward and easy to implement health habits you incorporate.

Intermittent fasting (IF) is a form of fasting that strategically times WHEN you eat throughout the day. The most straightforward method incorporates a feeding time during the day, after which you fast.


Why is Intermittent Fasting an Ideal Dietary Approach?

Humans evolved in circumstances where food wasn’t readily available, and our bodies were optimized to function well in the fasted state. Our bodies are no different today! When in the fasted state, our metabolism shifts to burn fat when it runs out of both sugar and stored sugar called glycogen.

In today’s world, we don’t need to hunt or forage for food. Food is plentiful and many of us have fallen into a pattern of eating all day long – morning through night. As a result, we burn sugar as fuel and never run out. Consequently, our bodies never need to make the metabolic shift into burning fat as fuel. Our bodies are not  adapted or evolved to thrive with this pattern and hence, this contributes substantially to the incidence of diet related disease. Those who never enter a phase of fasting miss out on the physiological benefits of the metabolic shift toward burning fat as fuel.

With intermittent fasting, we teach our bodies how to efficiently shift metabolic modes to efficiently burn fat as energy.

 Common types of Intermittent Fasting

  1.     16:8- the most common, this means fasting for 16 hours and eating for eight (for example between 12pm-8pm, which means you may skip breakfast but eat lunch and supper). You can start with a 12-12 and work your way up from there. This is the easiest to incorporate into a daily routine and make part of your lifestyle.

  2.    5:2- caloric restriction for two complete days of the week consecutively, eating normally for the other fives

  3.    24 hour fast (dinner to dinner), twice a week on non consecutive days




Weight loss- IF has been shown to have a bigger impact on reducing obesity than caloric restriction alone, most likely due to the fasting state.

  •   Fasting and ketosis are being correlated with conserved muscle mass in a calorie deficit. Basically, it is easier to keep muscle and lose fat.

  •     Burn excess visceral fat- the dangerous fat surrounding the organs that contributes to insulin resistance, diabetes, heart disease and inflammation

Mental Function and Energy

  •        Improves mental clarity, balances mood, and may improve anxiety and depression. Your body goes into a mode best suited for survival when you fast.

  •   Supports healthy aging of the brain

  • Blood sugar regulation improves with Intermittent Fasting (even in diabetes, though medical supervision is necessary).

  • Reduction in inflammation and oxidative stress (both contribute to accelerated aging)



Quite a lot of research exists with intermittent fasting. Below are a few impressive highlights.

·         Breast cancer recurrence significantly decreases in women fasting for more than 13 hours overnight (1)

·         Blood sugar regulation, as measured by HbA1c is improved in women fasting 13 hours or longer. (1) Another paper reviewing the effect of Intermittent Fasting on insulin dependent diabetic patients shows remarkable benefits including substantial weight loss and no longer requiring insulin. (2)

·         In asthma, alternate day fasting significantly improved control of asthma and Quality of Life. (3)

·         The physiological changes that occur with Intermittent Fasting are becoming more clearly understood as well. A recent publication demonstrated many more metabolic changes with fasting than had previously been imagined. (4)

1.       Prolonged Nightly Fasting and Breast Cancer Prognosis. JAMA Oncol. 2016 Aug 1;2(8):1049-55.

2.       Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin. BMJ Case Rep. 2018; 2018: bcr2017221854. Published online 2018 Oct 9.

3.       Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Free Radic Biol Med. 2007 Mar 1;42(5):665-74.

4.       Diverse metabolic reactions activated during 58-hr fasting are revealed by non-targeted metabolomic analysis of human blood. Scientific Reports volume 9, Article number: 854 (2019) 



The Role of Insulin! Insulin stimulates fat formation by mopping up extra sugar in the blood and storing it away in fat cells. The longer we fast, the lower levels of insulin our body will experience through the day. This is an excellent accomplishment for maintaining our health, as insulin not only builds fat, but also contributes to other illnesses.


Beginning Intermittent Fasting

Begin by establishing a regular period of fasting daily. Perhaps begin with a window of 12 hours fasting.

  1. Steadily increase your fasting window over the course of several weeks by one hour increments to reach the 16:8 pattern.

  2. Examples

·         Fast from 8PM until Noon – this may work best if your schedule dictates a later dinner.

·         Fast from 5PM until 9AM – this may be a better pattern for those with trouble sleeping.

·         Can these methods be used interchangeably? Yes, but creating a routine is a better foundation for health – it will support better sleep, energy, and circadian rhythm. But if on occasion you were to switch to the other approach it shouldn’t create any problems

Tips for the fasting period:

·         Your fasting window begins when you finish your last meal of the day.

·         It is best to do Intermittent Fasting every day, but if just beginning, you may choose just 2-3 days of the week. Pick your busiest days to do IF

·         Drink lots of water – STAY HYDRATED! (clear herbal teas are okay, e.g., ginger and green).

·         Black coffee or clear teas are ok to drink during your fast as they contain very few calories. Do not add milk or sweeteners, and do not have more than one coffee daily.

·         You can include a fasted workout in your routine

·         Expect Intermittent Fasting to get easier with time!

·         Break your fast with a HEALTHY meal!

o   Follow the Healthy Eating Guidelines and eat foods prepared at home

o   Refer to the new 2019 Canada Food Guide

o   Intermittent Fasting is not an excuse to eat junk or to binge through your feasting window. If it is leading you to make poor dietary choices, re-evaluate whether it is right for you.

o   Home prepared foods

o   Guidance on food sensitivities may be helpful to craft your ideal diet more individually

·         Make sure you are not consuming a larger meal than what your body needs – you do not need to over eat to compensate for a missed meal. Take your time to eat your first meal of the day, allowing yourself to recognize when you are full before eating too much.

·         Include protein at all meals, especially your first meal of the day. this helps to stimulate your satiety hormone leptin, and set you up for a better day.

·         You may enjoy 2-3 bigger meals during your feasting window or you may enjoy several smaller snack type meals - do whatever works best for you!



Should Anyone Not Begin Intermittent Fasting?

There are circumstances where it is best not to begin ones journey to better health with Intermittent Fasting. Typically, each of these ought to be addressed before beginning an Intermittent Fasting plan. Medical supervision is important to prevent problems

·         A poor quality diet

·         Adrenal fatigue or exhaustion (swapping to IF puts a small load on your adrenals, so it helps to make sure they are strong prior to starting). Support could include ashwagandha, reishi, rhodiola, magnesium and b vitamins.

·         Insomnia

·         High Stress or Anxiety

·         Blood sugar dysregulation: Diabetes or Hypoglycemia (medical supervision is necessary)

·         For women planning to conceive – best not to exceed a 12 hour overnight fast, and only then if cycles are regular

·         ** Intermittent Fasting is not recommended during pregnancy or lactation.


What type of monitoring might be helpful during Intermittent Fasting?

·         Testing Heart Rate Variability (HRV) to assess how your body is responding is useful

·         In some it can be a good idea to be measuring blood sugars every morning

Questions and Answers

How will you know if you have reached the Fat Adapted State? 

  • If you can work out/exercise while in a fasted state without feeling lightheaded or dizzy, you are probably fat adapted.


Do I have to reach my fasting hours every day? 

  • The aim is to achieve the fasting state every day, but No, there will be times for various reasons when you may be unable to fast your typical duration of time. Maybe you have been at a late night party, have a morning breakfast meeting, or are on vacation. It happens and it won’t undo what you have achieved. You will still be fat adapted and will still easily enter an efficient fasted state the following day. That said, you will typically feel so well with IF that even when on vacation you will probably still aim to maintain a duration of fasting


Will fasting slow my metabolism?

  • No! Research has demonstrated that metabolism will speed up with fasting. This is when we need energy the most, to gather/hunt food more effectively, we couldn’t do that if fatigued and low in energy.

  • Fasting is a great way to speed up metabolism in general and leave you feeling more energetic.


Won’t my body lose muscle while fasting?

  • No! The body has a secondary store of energy for just this circumstance. It’s fat!


My diet is really not very good. Is this the best way to begin an initiative to improve my diet. 

  • Work on healthy eating habits before attempting IF. You should know how to prepare a variety of healthy, delicious foods before attempting IF. 

  • Review our healthy eating guidelines and focus on these first.

  • It can be, but for someone who is constantly thinking about food, it may not be the easiest first step. In this case, beginning with a moderate fast overnight and focusing on choosing healthy foods through the day is important. We can’t get around the importance of the QUALITY of our foods, even with Intermittent Fasting!


What do you do if you are hungry?

  • Drink some green or ginger tea

  • The hungry feeling will most likely go away within the hour

  • Distract yourself with an activity



How long does it take to get fat adapted?

  • Usually about 2 weeks


What do you do if you have a special event?

  • Keep your schedule as best you can, come back to at as soon as you can


Is there a restriction on how much you can eat?

  • No restriction on how much or often. With a smaller window it tends to be less but that is not always the case


Can you take Apple Cider Vinegar, coffee, collagen, bone broth etc and keep the fast?

  • Anything with even slight calories will break your fast and make you hungry.