Fasting Part 1: Sharpening all the tools in the tool box

As an opener, since this is such a broad topic, I’ve decided to split this post into 2 parts. As I was researching for this article, I was becoming more and more intrigued by the benefits of an extended fast. I decided to run a trial experiment on myself and carry out a 3-day, 72 hour fast. The results were very interesting and I don’t believe many type 1 diabetics have tried this before. I will describe the whole experience in the second part of this post. I feel it’s important to first set the stage and get into the nuts and bolts of what fasting is, what its benefits are, and how these can translate to a type 1 diabetic.

So let’s get to it. Fasting? Like starving yourself? Who in their right mind purposely starves themself? Isn’t breakfast the “most important meal of the day”?

This was me, for most of my life. Growing up with the food pyramid and daily recommendations and keeping yourself constantly in a fed state to “keep your metabolism active” was how I understood nutrition and what was best for my body. As a type 1 diabetic (T1D), I was CERTAINLY taught that keeping a steady flow of carbohydrates was essential for proper T1D management.  Skipping a meal would undoubtedly result in a hypo (low blood sugar). This is still true, if a T1D were to just “blindly” skip a meal, however with a heightened understanding of one’s body and its functions, and how to tweak insulin with the intent of mimicking the pancreas, T1Ds can enjoy ALL the benefits of fasting (which are many), just like a non-typ1er. But let’s back up for a second here:

Intermittent fasting was something I came across fairly early in my dive into keto and keto living. I first came across it when I discovered Dr. Eric Berg’s plethora of educational videos on his youtube channel. I was definitely intrigued, but unsure how to proceed with T1D. Putting a lot of thought into how to approach it, and doing my due diligence with research, I decided to try it out. After a couple days and a few tweaks here and there, I ended up fully committing o a 7-days-a-week intermittent fasting routine with my ultimate goal being weight loss, and in hindsight, I truly consider it to have been a cornerstone to my weight loss protocol and success.

So what exactly is fasting?

Fasting is something each and every one of us does each and every day. The duration varies from person to person, day to day, but our bodies are designed to function, process, and heal during a state of fasting. Simply put, fasting is the time you spend between meals, or when you just stop eating. The most common period of fasting that most people can relate to is the overnight fast, broken by “break-fast” every morning.

Fasting has been around since time immemorial. I find it fascinating to look at human health and diet through an archaeological lens. Not getting into WHAT we’ve evolved to eat (that is just WAY too large a topic!), but focusing instead on what’s evolved in our bodies WHEN we eat (or don’t eat, it turns out). As discussed in my previous blog post on ketosis, we as humans have adapted to function, and incidentally thrive, during periods without food.

There are so many powerful effects in the body that occur when we fast. It’s when our bodies reset, heal and grow. I’m going to delve into what happens in our bodies when we fast, different types of fasting and how fasting can be used as a tool in the type1 diabetes management tool kit.

Types of fasting

Time restricted eating:

Time restricted eating is basically when you limit your eating to a specified time window during the day. There are several different options:

Fasting/Eating windows: 14:10,16:8,18:6, 20:4

Each of these represents hours fasted – eating windows. As stated in the next section of this post, the benefits increase with the longer periods of fasting. Jumping right into an extended fast though may be really challenging both physiologically and psychologically. Starting off with a restricted eating window is a great way to ease into fasting. The most common one is the 16:8, where you fast for 16 hours, say 8pm until noon the next day, and consume 2 normal sized meals in an 8 hour window – in this case, lunch and dinner. This is the protocol I myself followed when I was doing intermittent fasting as part of my weight-loss protocol. I chose this fasting approach because it offered the best of both worlds – I was able to lose weight by having a calorie deficit, and also enjoy the other benefits of fasting, which will be discussed further.

OMAD – One meal a day. This strategy is pretty self explanatory. It’s when you fast for 22-23 hours and consume one meal in a 24 hour period. It doesn’t matter the time of day, this will come down to personal preference although for a diabetic, nutrient absorption should always be considered when making insulin decisions, so tin several hours before sleep is usually advised.

Extended fasts

Extended fasts can last anywhere from 24 hours to multiple days – like 2 weeks or more in some cases! I have included a fasting timeline in the below section under “autophagy” where the different benefits kick in and when. Common extended fasts usually are around 3-5 days (this from my own observations from peoples’ experiences on podcasts and social media).

Why oh why would someone choose not to eat for multiple days in a row? Let me explain.

Benefits of fasting

Hormonal balancing – INSULIN

New ways to view the obesity epidemic are coming to the forefront that shed light on insulin as the main culprit for weight gain and obesity. Among its many jobs, insulin is a storage hormone – a signaller for the body to store fat. When I discovered this, it made total sense why for my whole life (no matter what size or activity level) I’ve had an “insulin pouch” in my mid-section. I used to think it was scar tissue from injections or just genetics, but as it turns out, it’s a bi-product of manual injections, and insulin resistance.

Keto can help immensely with healing a broken metabolism and giving your system a break from overworking the pancreas, or in a T1D, manually giving massive amounts of insulin. Just cutting carbs can lower insulin need and result in lowering insulin levels. However fasting, especially when combined with keto, can significantly increase this “break”, allowing your body to reset and become more “insulin sensitive”. Plus, then your body is already attuned to dialing into its fat stores for energy. In my opinion, Insulin sensitivity should be a goal for every diabetic and non diabetic person, as it demonstrates a healthy metabolism and means that large amounts of insulin aren’t required to absorb and transport energy (glucose) around the body – resulting, by default, in less unnecessary weight gain.

In his book The Obesity Code, Dr. Jason Fung makes several important points that back this all up. He states that simply put, the more insulin you use, the fatter you get. He cited a study using T1Ds where 2 groups over 6 years were observed, and the higher insulin group gained 30% more fat than the control group. Interesting, I discovered through reading his book that longer fasts mean that fat is converted into energy through gluconeogenesis as well – I thought this was just a protein to glucose conversion. Incidentally, when there is no intake of food, insulin levels fall and burning of sugar and fat is turned on. Therefore, states Fung, fasting is the most effective, consistent strategy to decrease insulin levels. Blood glucose (BG) levels return to normal as the body switches over to fat burning for energy.

So to sum it all up, regular fasting routinely lowers insulin levels which has been shown to significantly improve insulin sensitivity. By default, this reduces insulin resistance, which is the key to weight loss – on to the next section!

Fat-burning/Weight-loss strategy

As discussed in the previous section, fasting is a powerful tool for lowering insulin need, and subsequently, fat storage. There is a far less complicated explanation as well (that leaves out hormones etc) that is important to mention. It’s simple math!

Every body has its calorie demand for the day. Many factors contribute to this, ranging from age, sex, activity level and genetics. For simplicity sake let’s call the range from 1800 – 3000 calories a day. Calories-in need to be balanced with calories-out, or excess gets stored as fat for future use. It can therefore be surmised that if you have excess weight to shed, eating in a calorie deficit (fewer calories than your daily need) will result in your body tapping into its energy stores.

This is a fairly accepted standard for weight management. I believe it’s actually far more nuanced than that, but I’ll save that for another post! Generally though, I do think this approach works, but what’s the best strategy? Eating a bunch of mini-meals that never fill you up? That doesn’t sound appetizing (pardon the pun!), does it? By taking an intermittent fasting approach, say the 16:8, you can choose a meal to skip (for me it was breakfast) and eat 2 full-sized meals giving yourself the satisfaction of being sully satiated whilst still cutting down on your daily caloric intake. Win!

This approach is a really feasible, attainable way to dip your toe in the fasting pond. It allows you to enjoy many of the benefits of  fasting while still feeling like you aren’t super restricted.


Autopha-what? This is a benefit of fasting I discovered when diving deeper into my research of the practice. If you look at just the word itself broken down it means “auto”- self, and “phagy” – eating. Self-eating? Cannibalism? Ha! No, more like “self-cleaning”. It’s a metabolic process where cellular debris, free radicals,  and dysfunctional organelles get “cleaned up”, or  self-eaten by the body. It’s been touted for having “anti-aging” properties as it’s a great way for your body to get rid of its dead, broken or dysfunctional cells.  While this is going on, growth hormone can also be switched on. These factors all piqued my interest and made me curious about trying an extended fast myself.

There are two main ways to spark autophagy in your body: exercise and fasting. It comes into effect with a  lower insulin – glucagon (which is a key hormone used by the body to regulate glucose and fat utilization) ratio which occurs several hours into a fast (usually 18-20 hours) after the glycogen (back-up glucose in the liver and muscles) stores have been burned through and insulin levels lowered. For autophagy to fully kick in the body usually needs 36 – 48 hours of fasting. This can be sped up though through other means such as exercise.

The most common ways to induce autophagy are: extended fasts, time restricted eating, calorie restriction, carbohydrate restriction, cardio done in a fasted state, resistance training and deep sleep. Basically the main mechanism is energy depletion (which is achieved in most of the above list) and increased catabolism (basically the breaking down of molecules, versus anabolism, which is the “building” of molecules).

There are several benefits commonly discussed surrounding autophagy: it can strengthen your immunity, eliminate pathogens, remove zombie cells and protect against neurodegeneration and inflammatory diseases.

I’ve borrowed the following timeline from Siim Land, who is someone I follow and know to have a deep understanding of fasting and its benefits/protocols. He’s written several books on the topic, most recently one titled Metabolic Autophagy.

Fasting timeline:

  • 4-6 hours – blood sugar begins to drop
  • 10-12 hours – liver glycogen is being tapped into
  • 12-14 hours – ketones begin to rise
  • 18-20 hours – fat oxidation increases markedly
  • 22-24 hours – liver glycogen has been depleted
  • 24 hours – gluconeogenesis rises progressively
  • 24-36 hours – growth hormone spikes exponentially
  • 36-48 hours – autophagy increases
  • 48-72 hours – ketosis and fat oxidation rise exponentially
  • 3 days – gluconeogenesis peaks and begins to decrease
  • 3-5 days – ketones rise multifold and reduce muscle catabolism
  • 3-5 days – blood sugar drops the lowest
  • After day 5 – growth hormone increase flattens out
  • After day 5 – muscle catabolism will begin to increase again
  • 7 days – metabolic acidosis and ketoacidosis increase

*To see the original post, click here.

I noticed that the benefits I personally wanted to experience all landed in the 24 – 72 hour range.

Uses of fasting: both past and present

Let me first clarify the difference between fasting and starvation.  Starvation is an involuntary nutritional deficit over an undetermined period of time. Long-term, undetermined starvation will lead to complications surrounding nutrient deficiencies.  Fasting however is a conscious, intentional “pause” in feeding, used for cleansing our bodies. In our history, conscious fasting has really existed in two realms: medical and spiritual. The Ancient Greeks noticed that humans, like animals, do not eat when they are sick. Hippocrates, the name-sake of the Hippocratic oath taken by all modern day doctors, was a huge proponent of fasting. He commented on the healing powers of fasting, toting its benefit over administering medications. Major players in medicine throughout history have been supporters and implementers of fasting, but I won’t get into a major history lesson, conscious of veering off on a tangent!

As we see fasting appear as a medical treatment throughout history, its spiritual use has been applied in religious contexts around the world as well. Where religions may not base the practice of fasting through the lens of healing the body, healing the spirit and “cleansing the soul” are often cited. Mental clarity, or increased cognition, is often touted as a benefit of fasting and likely (this is my own deduction here) leading to moments of spiritual clarity. I do not profess to be an expert on religious practices and don’t intend to veer in that direction either, but my personal deduction is that the mental clarity is very real and could easily be applied to a spiritual awakening thanks to elevated ketone levels during a fast and the effect we understand them to have in terms of cognition and neural-firing.

How can fasting benefit T1D?

As I began researching for this article, it became clear that there hasn’t been a great deal of research done into the benefit or utilization of fasting as a tool for T1D management. There is a lot of support for it as a tool for managing type 2 diabetes in terms of weight loss and lowering insulin resistance, but there is a serious lack of research into type 1. I can say with certainty, as I was one of them, that T1Ds can suffer insulin resistance as much as a type 2 can, so the benefits discussed previously can definitely apply to a type 1 diabetic.

Through diving deep into the benefits of autophagy and extended fasts for this article, being the person I am (not allowing diabetes to stop me from doing anything!) I decided that I wanted to give an extended fast a try. Not eating for 3 days – this would be a serious test for my understanding of my body and its insulin requirements.

So I did it and survived! I’ve decided to document the whole experience in a separate post, as I don’t want to bog-down this article and I think the experience deserves detailed attention and analysis.

In terms of managing my own personal diabetes, I have found intermittent fasting to be very powerful. It allowed me to lower my basal insulin levels, which means over time lower fat storage thanks to the reduced insulin. I found that combining the 16:8 window with a ketogenic diet highly effective because my body was already adapted to utilizing ketones for energy, and thus tapping into my stored fat – which was only heightened by intermittent fasting.

Important considerations

As with almost every aspect of life, T1Ds need to take extra precautions with fasting. Not only is there the increased risk of hypoglycemia (low BG) but risk of the opposite, hyperglycemia (high BG) if insulin balance is off. Blood acidosis can occur in longer extended fasts in a non-diabetic person, so the danger of ketoacidosis is an increased risk for a T1D on an extended fast. If you, fellow T1D, are curious about experimenting with a longer fast to experience the many benefits of fasting, I would recommend you do so with the guidance of your diabetes health care professional. Discuss basal insulin rates and how much to drop your insulin levels over the course of the fast. T1Ds have successfully been guided through fasting, especially surrounding the Muslim practice of Ramadan, so it can be done, and has been done in clinical settings. You will want to be sure you have a deep, nuanced understanding of your insulin needs and ensure that you have done adequate research yourself. Knowledge is power, and is the key to unlocking the powerful tool of fasting and type 1 diabetes management.


Type 1 diabetes and prolonged fasting

Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus

Siimland blog – fasting benefits timeline

Autophagy and Neurodegeneration: Pathogenic Mechanisms and Therapeutic Opportunities

The Effects of Calorie Restriction on Autophagy: Role on Aging Intervention

LCHF for type 1 diabetes

Can type 1 diabetics do prolonged fasting?

Intermittent Fasting and Type 1 diabetes

The real skinny on fasting 

Fasting with Type 1 Diabetes

The best ways to activate autophagy

Amazing Benefits of Extended fasting

What really happens when we fast?



Leave a Comment

Your email address will not be published. Required fields are marked *