Intermittent fasting and insulin – Part 1, Introduction

Getting older is a real bitch. I know that everyone says they could get away with anything when they were in their 20’s, but I really pushed it. I ran marathons in brand new shoes. I drank until I had holes in my brain without noticing any cognitive decline. I swore off recovery weeks. I did so many things that you’re not supposed to do that soon I started pushing the limits on purpose to see what I could get away with, and I got away with it. I ran over 18 miles a day, 5-6 days a week for 6 weeks and actually got faster rather than becoming overtrained. I did nothing but endurance training, and still was able to deadlift more than most of the women in the gym. So why wouldn’t I think I was invincible? Our bodies are amazing superorganisms that regenerate themselves over and over, and my body felt just a little extra super. Normal limits did not apply.

giphy9The flip side of getting away with everything was that ability to change my body also seemed like a bit of a hoax. I tried to eat less and exercise more, but no matter how well I ate or how much I exercised (and god, I exercised a lot!) my body always kind of stayed the same size. Sometimes I would get really extreme and lose maybe 10lb, but pretty soon I would stop running 80 miles a week or start eating processed food again, and I’d come back to the same weight I’d been since I was a freshman in high school.

My weight wasn’t my only “set point” either. I tried modifying my running form, and did a bunch of exercises to stop being a heel striker. The drills didn’t work. I tried all the conventional periodized training methods over the years as well with running and cycling, and never really saw any results that were different from when my training was intuitive and disorganized. My body was just going to do what it was going to do. Why fight it? Why bother to pay attention to all of those lifestyle things that they say are bad for you?

But then, much to my surprise, after I’d been 29 for 365 days in a row there was no special next step reserved for me that wasn’t available to mere mortals; I too turned 30. And even more surprising, all of the things that they say start to happen when you’re older also started happening… to me! It took me longer to recover from my workouts. I was stiff all the time. Advertisements aimed at millennials stopped looking cool and started looking kinda dumb. I didn’t feel the urge to take to the streets and fight The Man every time there was a headline that reminded me that the world is an unfair place. It wouldn’t take weeks of crappy eating before I saw changes on the scale, one meal from the Cheesecake Factory and I would gain 3lb permanently. Performance gains were harder won, and lost more quickly. And when I went for my annual physical and got my blood work done, I saw something that I’d never seen before: a red font.

giphy10I quit smoking and drinking years ago, but I do have an irredeemable sweet tooth. I’m one of those people that if it’s available, I will eat sweets with breakfast, lunch and dinner, and every snack in between and not even notice that I’ve made the nutritional choices Augustus Gloop. When I’m stressed, I eat dessert to my dessert. What this blood test was telling me, and the next 3 thereafter would confirm, was that I was no longer getting away with it. My hemoglobin A1C, a measure of how well your body is handling its glucose (i.e. how healthy your blood sugar and insulin reactions have been over the past 3-4 months), was right on the line of becoming prediabetic. HbA1C (I’ll just call it A1C from now on) isn’t like your blood sugar that goes up and down over the course of the day and so could register abnormally high if I were tested on a bad day. It is a measure of how your blood sugar has been doing for the past 3 or 4 months.

The first time it came back borderline, I just ignored it. It was Christmastime after all, but I don’t eat as many cookies throughout the year as I eat at Christmas, right? But then the next few tests over the next few years showed that maybe I actually do eat that many cookies, or cakes, or pastries, or ice cream, or stress-induced Laffy Taffy… I wasn’t deluded enough to think that I “needed” sugar to be healthy, but I always thought that being an endurance athlete gave me a pass. Endurance activities empty your muscles and liver of glycogen, so with my morning run every day I was emptying my tank. So when I ate a baby’s-head-sized muffin with frosting for breakfast, my body would just scoop up all that extra glucose in my blood and put it in my muscles for use on tomorrow’s run, rather than let it circulate around in there and do damage. Right?

smokestacks.jpg.662x0_q70_crop-scaleApparently not. From what I’ve read, what A1C actually measures is how many of your cells are glycated, or covered in sugar. High blood sugar is a bit like if there’s a big smoke stack on your way to work. If that smoke stack is constantly spewing out black smoke and you drive through it every day, eventually after daily exposure your car will get covered in soot that will never wash off. Once a cell gets glycated it stays that way until it dies at 3 or 4 months old. So enough of that muffin was not being used for running. Instead all that glucose was floating around in my bloodstream like that sooty smokestack, and eventually all my little red blood cells were getting covered with the crap.

What had started as some casual googling to figure out what I was doing wrong turned into a mild obsession. There really seemed to be something here in this whole blood glucose/insulin thing. At first I was skeptical. I had found the information on the internet, after all. And there was an awful lot about fasting, which everyone knows is a bad idea… right? But the more I read, the more the pieces started to fall into place.

I worked my way inward from the kooky blogs and vlogs that first turned up in my scattershot Google research back to the scientifically-sound and research-backed gravitational center that this mixed bag of resources revolved around: Dr. Jason Fung’s The Obesity Code. Usually I don’t put myself through the torture of reading a nutrition book without a solid recommendation because they either state the obvious with 300 pages of common sense, or because they set off my bullshit meter in the first 5 pages. I read and watched everything I could about Dr. Fung with a critical eye, sniffing around for the slightest whiff of bullshit, but everything I found passed the sniff test. It made sense with everything that I knew about human biology, it checked out with my own experience, and it cited legitimate medical sources. I won’t try to cover his entire thesis here: the book presents his theory far more logically than I ever could, and provides the footnotes for the studies that back what you wouldn’t believe me if I told you. A very brief summary is: elevated insulin levels and decreased insulin sensitivity are the main factors that lead to weight gain (not excess calories, or certain types of food); and insulin is also the key to what makes it so hard to lose weight and keep it off.

No wonder I could never lose weight no matter how healthy my diet was, or how much I exercised! Here’s how I understand it:

If you remember high school biology or have ever spent much time with a diabetic, you know that when you eat food, especially carbs, your blood sugar goes up. Then your body secretes the storage hormone insulin, whose job it is to get that glucose get into the cells. Glucose levels that are either too high (from too many carbs all at once) or too low (from too much insulin) are bad. In a healthy body, your insulin can keep the whole operation under control. If you overdo it a little bit on the sugars one day, your body just secretes a little more insulin and the cells get a little overstuffed that day. No problem. If you don’t need any more glucose in the cells, well then it’s cool, it’ll just get converted into fat for later.


In a world where the only meal options are things like brown rice, sautéed vegetables and roasted chicken with a piece of fruit for dessert you’d have to go pretty crazy on the peaches to push your blood sugar up over 200 mg/dl, and you would probably learn your lesson and not do it again. Or certainly not the next day… or even at your next meal, anyway.

But we live in a way more exciting world than that! We have sugar, and white flour, corn syrup, and white rice, and all kinds of processed deliciousness. We can make these things into so many flavors, that you could eat them for breakfast, lunch, dinner, dessert, 3 snacks a day, and in our coffee and drinks in between. Plus, sugar makes everything taste better. So we put it in everything. Too bad it’s addictive, and the more we have the more we want. Anyone who’s followed me this far is probably a pretty smart person, so I’m sure you already understand where this is going: constantly high insulin from trying to deal with enormous hits of sugar many, many times a day. And as you probably know, your cells eventually tune out constantly high insulin, and it can’t do its job of clearing all that extra glucose out of your system anymore. The vicious cycle of secreting more and more insulin because it is getting less and less effective is what leads to Type 2 diabetes. My A1C levels were telling me that my insulin was doing such a crappy job that I had enough glucose circulating in my system all the time that it was doing permanent damage to my little red blood cells. They were coated in the stuff and looked like the cells of someone on a crash course for diabetes.

eTyqVrlAnd I felt it. I felt like I was always chasing a dragon with food. I spent the whole day thinking about my next meal, and wondering how soon I could eat it. I would do a body scan for signs of hunger every 15 minutes or so to see if I could possibly justify a snack. I was forever struggling to maintain the balance between eating everything I fantasized about, and not eating so much that I wouldn’t be able to eat again soon. I exercised over 2 hours per day so that I could be hungry for each of the daily meals that I had contrived for myself: first breakfast (4:30am), second breakfast (6:30), third breakfast (8:00), mid-morning snack (10:30), lunch (noon), dessert (1:00pm), afternoon snack (2:30), stress snack (3:30), dinner (7:00) and dessert (7:45).

I was never really hungry, but sometimes I had to eat a snack to prevent my previous snack from creating problems. For example, one day I ate a bowl of Froot Loops for afternoon snack around 2, and when I rode my bike home from work 3.5 hours later I bonked badly after only about 20 minutes and rode the final 15 minutes home shaky and weak. When Oscar jumped on me as I walked in the door, I thought I was going to topple over backward.

I also felt exhausted and used up. I was apathetic from the brain fog of the meals where I overdid it with too many servings, or too many sweets. I was run down from the working out and never feeling like I could take a day off. I also felt drained from constantly digesting something every minute of every day. One afternoon I realized that I couldn’t remember the last time I had actually felt hungry, and even that thought made me feel like I wanted to sleep for a week.

Meanwhile, one of the partners at work had started this extreme fasting regimen. He would go days without eating, then resume eating normally. Everyone thought he was crazy, but he had lost something like 60lb in a few months (at this point, I think he’s closer to 90lb). I knew this guy, he was one of the brightest people that I had ever met, and although Contrarian is his middle name, he never called bullshit on anything without a very logical and well-supported argument. Emotionally he was approaching the whole thing with curiosity and delight; he did not seem to have an eating disorder. When he was eating, he ate normally, neither binging nor doing the weird food ritual stuff that people with eating disorders do.

He is a curious guy and also a man of means, so once he started having some success he started getting all kinds of tests done. Far from saying he was deficient, the tests indicated that he seemed to be getting healthier, even after days without eating. Every time I spoke to him, I wanted to hear all about his latest experiments and what he was learning about his body. Nutrition is such a murky topic with more misinformation out there than actual experiential data, so I sucked up all the information that I could from his experiences.

I started reading about fasting. Everything that I read turned conventional wisdom on its head, but was in line with Phil’s experience. From the testimonials of people who had actually tried it, fasting made them feel great, made their health numbers improve, and research seemed to indicate that it was actually healthy for you. Despite a writing style that didn’t inspire much confidence in its legitimacy, The Complete Guide to Fasting from good old Dr. Fung and Jason Moore lit me en fuego.

I started playing around with baby fasts myself, I paying attention to how I felt. My evenings were more relaxing when I skipped dinner not just because I had more time when I didn’t have to cook, but I also didn’t have the anxiety of threading the needle between satisfaction and gluttony one more time before bed. My workouts didn’t seem to suffer for not having anything in my system the following morning, even if I skipped my first pre-run breakfast. I liked the feeling of not having a big meal constantly working its way through my guts. My HRV suggested that I was actually recovering better when I didn’t have dinner than when I did. I started to wonder if there really was something to this “nutritional stress” thing.

And for the first time in my life, I was able to lose weight the way that the “calories in vs. calories out” math seemed to suggest. On days when I skipped meals, I tended to eat just as many calories as when I painstakingly ate small low-calorie meals every few hours. But because I was eating less frequently, the meals that I did eat were heartier and more satisfying and it didn’t bother me that I was going to have to wait several hours until my next meal.

confusedWhen I thought about it, it made sense: Fat is the energy you store for when there isn’t enough food available to support all of your activity. If you’re eating constantly, even if it’s in small amounts, then your body isn’t going to be inclined to break down fat because you’ve constantly got glucose flowing around in there for your muscles and brain to put to immediate use. You don’t pull from the savings account when there’s still money in your checking account. If high circulating blood glucose is a constant problem, my body wasn’t about to try to spare my glucose and glycogen stores by using fat for fuel. It was going to try to burn up as much of that shit as it could. But if there are periods where my last meal is digested and gone, then my body would have to choose between stored energy sources: the finite glycogen or unlimited fat. By constantly eating every couple of hours, I wasn’t giving my body the opportunity to make that decision.

To turn things around, first I had to reduce the amount of time that my body spent with all that fat-stuffing insulin around. Then I had to figure out how to lower the amount of it that my body secreted with each hit.

Another thing that I kept reading about fasting was that it could reverse Type 2 diabetes. Type 2 diabetes is just your body becoming blind to its own insulin like a crazy cat lady becoming noseblind to the smell of cat piss in her house. If the old lady goes to stay with the grandkids for a few weeks or months and is away from the cat piss, then she’ll become smell it again when she gets home. Same goes for your body’s reaction to its insulin, apparently. What person given the chance to reverse any symptom of aging — be it wrinkles, disease, loss of physical function or mental decline, or the ability to digest a cupcake — wouldn’t take a chance to turn back the clock.

Possessed of a vague understanding, a theory and several anecdotal stories, I decided to learn from my own body. But how to get a view into my own insulin reactions, or lack thereof? There is one group of people whose lives depends on their ability to very closely and accurately measure their glucose/insulin balance: diabetics. All I needed to do was get my hands on a blood glucose test kit.

I’m not going to get into a rant about the cost of medical supplies, but if they are not cheap with insurance, the cost is downright prohibitive without insurance. I’m pretty sure that if (when) CGMs were marketed to the general public, the cost would be $300-500, but since medical supplies are paid by insurance companies and not individuals, there is no incentive to charge a fair market price. For a simple finger-stick blood glucose test kit I laid down about $150 for the monitor, test strips and lancets. The test strips were behind the counter, and when I asked the pharmacist to sell them to me without a prescription she could not understand the request.
stock-photo-lost-and-need-help-beautiful-young-female-pharmacist-looking-confused-and-helpless-gesturing-with-553522054“But why do you want them if your doctor hasn’t told you that you need them?”
“Because I want to understand my own body so that I don’t get sick someday.”
“But if you’re not sick, you don’t need them.”
“No, I don’t need them. But I want them. That’s why I’m willing to pay for them without a prescription.”

Eventually she just shook her head and sold them to me. But after that experience I wasn’t about to ask her how exactly the testing worked. First, I couldn’t figure out how the spring loading mechanism worked on the finger sticker so I spent a lot of time squishing up my face, gathering my courage, and just poking at my fingers with a naked needle. Then I couldn’t figure out if the test strip went in the machine before or after I got it all bloody. I wasted many strips this way. And which part of the strip was I supposed to put the blood bubble on anyway? The tip of the paper, or dribble it from on top onto the texting canal? Even more strips went in the trash as I tried to figure that out.

With all the challenges to manual testing, I kept forgetting to do it. Even on the best of days, only having 3 or 4 measurements at random times didn’t give me much of a picture of the actual arc of what my blood sugar was doing throughout the day. The whole experiment was pretty useless. So when I found that I had $800 in my flexible spending account that was going to go away at the end of the year if I didn’t spend it on something medical, I decided that I would use that money to buy myself a continuous glucose monitor.

Even though a continuous glucose monitor (CGM) is not a drug, it proved difficult to get one without a prescription. I ordered a Dexcom G5 sensor from the Dexcom site, and it required that I create a user profile, but they let me enter my credit card number without a prescription. I was relieved and excited for about an hour until I got an email explaining that they wouldn’t send my monitor until I filled out my doctor’s information. Well shit.

I had no problem discussing my experimentation with my doctor, but even a discussion could cause my appointment to be coded differently. Since diabetes is an incurable preexisting condition, I was being very careful about not creating any trail that might point to it on my medical records. Luckily, I have a friend who is a doctor and agreed to let me provide his information, as long as I wasn’t trying to get my hands on any drugs or anything. Once I had filled out the form I was excited for about another 20 minutes until got another email asking for my prescription. Well shit.

My doctor friend insisted that as long as I paid out of pocket and didn’t go through insurance, a prescription wouldn’t go on any “permanent records.” I sure hope he’s right.

feature-imageSeveral business days later, my Dexcom G5 continuous glucose monitor transmitter showed up in the mail and I eagerly opened it. It was a little pod about the size of a Jordan Almond and it came alone. No needles. No adhesives. No tubing. I had no idea what I was doing, but even I knew that this thing had to stick to my skin and reach inside to where my blood was somehow.

A little more research revealed that I would need to buy a separate sensor that came with a really imposing looking plunger and wrapped in a really un-sexy looking sterile package. It didn’t look like a fun little gadget, it looked like something that a sick person would use. This time I wasn’t messing around with buying the materials directly from the manufacturer, I was going right to the black market: ebay.

Weeks later I finally had all of my supplies. I had planned to have a diabetic coworker show me how to put the sensor in for the first time, but I kept forgetting to bring the stuff into work. So I did the same thing that I do whenever I need someone to show me how to do something: I turned to Youtube. I suppose it should have occurred to me sooner, but I was shocked that my $50 sensor would have to be replaced… weekly! For some reason I thought that it was like a chemo port or something and once inserted it stayed in there forever. Man, how did people without insurance manage this stuff full time?!

Sensor inserted, I excitedly downloaded the app, paired my transmitter, and eagerly awaited the 2 hour calibration period. When the 2 hours were up, I got a notification: Test your blood glucose to calibrate your device. What?!?! At least I had plenty of test strips left for this calibration reading. Once I entered it, the app told me, “Great! We’ll check back with you in 12 hours for your next calibration.”

“Yeah, I’m not doing that…” I thought, remembering that my test strips had cost like $1 each, and I still couldn’t figure out how to take a reading without wasting at least 2 of them. That night I ignored the alerts to prick my finger again and went to bed. Well apparently, if you don’t follow the rules, this app can override all of your do not disturb settings and emit a loud, sleep-shattering beep every 30 minutes until you feed it a new value. There is no way to turn off alerts. I understand why that would be a life-saving setting for someone who couldn’t regulate their own blood sugars, but this was just a toy!

Finally set up, I was ready to start learning all about my insulin from my blood glucose, which is a little bit like learning about someone by only observing their shadow. In other words, blood glucose is not an exact mirror of insulin levels, since blood glucose can go up or down in the absence of insulin and insulin can be secreted without eating carbs. But whatever, close enough. I was ready for my uncontrolled science-like experiment.

Hypothesis: Intermittent fasting can increase insulin sensitivity and reduce overall insulin levels.
Second hypothesis: Too much insulin is what makes you fat, and what makes it hard to lose weight.


  • Use my continuous glucose monitor to learn patterns of blood glucose and how it reacts to factors such as food intake (is eating white bread really the same as eating a piece of cake?), fasting (will I really go hypoglycemic if I skip meals?), exercise (when I feel like I’m bonking, am I really hypoglycemic?).
  • Eat all of my meals between 8am and 2pm (i.e. skip dinner), and do my workouts in a fasted state. Observe whether I die. Observe effect on blood glucose.
  • Give up sweets. This one I didn’t really do for the experiment, I was going to do it anyway. I decided not to give up all sugar because it is in everything, but give up all cakes, candies, granola bars, cookies, pastries, ice cream, muffins, doughnuts, frosting… That was something that I thought I could commit to… for a time anyway


  • A1C
  • Daily high and low blood glucose
  • Weight
  • Body fat
  • Late workout heart rate data (since higher heart rates correlate with using more glucose instead of fat, a lower late workout heart rate would indicate higher fat utilization)
  • Subjective experience

Next up: Observations

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