Irritable fasting and the one line you shouldn’t cross
In my first post on intermittent fasting I focused on one of the major benefits of this hunter-gatherer regimen: mental focus. Over the last three years, though, I’ve noticed some detrimental effects from IF for me personally that often counter the benefits.
I find that this “diet,” if I can call it that, gives me clarity and drive in the morning in addition to the body-composition benefits that are both anecdotal (pour moi) and to large extent backed by science. Put simply: to those who are looking to simply lose weight, there is more than enough evidence to at least try IF. 
Although keto gets the lion’s share of all diet-related claims of greater focus and clarity, the whole point of my original article was that I personally experience an effect similar to keto when I fast through the morning.  Science, logic, and personal experience lead me to hypothesize that this focus is created by a mix of metabolism, avoidance of “puppy belly,” and hunger. The last one, the actual ‘starvation,’ isn’t really as bad as most people think.
So, what kinds of ill effects can come from intermittent fasting? And how? For God’s sake, man, tell me why?!
The Vantasner Danger Meridian.
The Vantasner Danger Meridian
According to at least one high-level CIA official who also spent significant time on a remote island occupied by Others, the VDM is defined as follows:
the point or line after which danger to your mission and/or sense of self increases exponentially. Often used to demarcate conditions of grave and approaching danger.
The Vantasner Danger Meridian can be regarded as a kind of tipping point. A Rubicon in daily life. Unlike Julius Caesar, though, you might cross this point-of-no-return without knowing it.
When you’re restricting food intake, there’s a line beyond which the faster can become, well, slower. You become tired. Or anxious. Or both tired and anxious at the same time. You lose the big picture and focus on tactical to-dos like email. You become more terse and less cordial. Exactly when and how this hits you varies from person to person and from day to day. It depends on what and how much you ate before as well as your own metabolic profile.
Some nutritionists classify this experience as being hangry. However, as many seasoned IF-ers attest, the feeling can be somewhat different than hangriness, especially if you’re getting plenty of low-glycemic calories during “feed” periods. Plus, the hunger itself doesn’t bother you as much as it did when you began fasting. I’ve noticed that fatigue past the Vantasner Danger Meridian on any given day is worse than morning hunger outside of IF.
It’s almost as if the drive for food is filtered through some abstraction layer between your body and mind. Your thinking and emotions get a little squirrely. And because you’re so driven and focused, you keep trying to solve things. Just maybe not the right things.
In many cases fasters can channel increased mental sharpness into productive ends. I’m writing this post right now on an empty stomach. It’s almost 12pm now at my cartographic meridian, and I may not eat for another couple hours.
Some days, though, my IF-driven ends are more sinister. Okay, I’m not killing cats or spying on my neighbors. But while it is tempting and even fashionable to regard focus as something uniformly beneficial, focus can sometimes be a negative experience. It’s like a superpower that a protagonist should use for good but sometimes doesn’t.
Rather than being purely positive, my personal experience is that intermittent fasting magnifies my mental state, whatever it is. It functions as a near-literal lens for my thoughts and emotions in a way that is non-judgmental.
I’ve said many times on my podcast that we are “wired to win.” But it’s not assured that we actually want to win the game our brain is playing. We have to train our mind’s spotlight on things that truly matter to us. Let’s win those games.
Sometimes, we don’t have a choice about what game we’re in at the moment. On mornings where I wake up to a ton of meetings about ‘piping’ with my boss, Leslie, I’ll be sitting there like that guy Lakeman ready to shoot myself in the head.
Patriot’s protagonist, John Lakeman, is on a critical mission. But he’s forced to play a part as a ‘piping’ engineer. We’re all forced to play parts at times. But it’s those days that I’m doing unfulfilling work that intermittent fasting ends up making me feel more frustrated than I already would be. In those moments my hungry mind is trying to win a game with shitty prizes. One that is probably unwinnable.
There is evidence that intermittent fasting may increase levels of the stress hormone cortrisol. One blogger who reports thoroughly on his(?) experience on IF confirms the seemingly benefit and harm to focus and productivity that would seem to contradict each other:
I’ve noticed that there’s a sweet spot every day — a time period to stop your fasting window. If you break your fast too early, you’ll miss out the energy that could’ve been used to get more work done. If you break your fast too late, you’ll start to get agitated and lose focus during the day.
Having extra drive is frustrating when you’re not in the right place. You’ll feel like you’re running into brick walls over and over. And like an idiot you won’t quit. You’ll become even more reactionary. You might even drink loads of coffee to fill both the mental and gastrointestinal void. Caffeine turning this magnifying lens called intermittent fasting up to 11. Amplifying your ennui, which is sitting a tad too close to the amp right now.
So if you’re doing IF, do your best to find that place quickly.
But first, breakfast.
About the author: Sri hosts The Warrior Poet podcast, a show on the philosophy of leadership based on his experience in the SEAL Teams, at Harvard Business School, on Wall Street, and in tech. Shows every Monday. Follow him on Instagram @sri_the_warrior_poet and @sri_actually.
All the way wet (aka the footnotes)
 “All the way wet”: Something an instructor might say to students at Basic Underwater Demolition/SEAL training.
 I’d recommend combining with exercise like HIIT or strength training plus low/slow-carb nutrition. Keto works like magic but necessitates significantly more work and knowledge.
Separately, I use quotes for “diet” in this case only due to IF’s focus on timing of food intake and agnostic regard toward the actual quality and quantity of that intake.
 I don’t write Cliff’s-Notes recyclations (a real word as of now) of scientific studies, nor does this author echo things that everyone will agree with just to get likes. Thus, this is not a full indoctrination into IF nor a widely appreciable singing of its praises. But I’ll note that the timing of the fast that I use is just one of many options, though it is likely still the most popular formula. Increasing in popularity now: systems that drastically cut calories for one or more whole days during the week. I’m not endorsing them necessarily; it’s just that sharing is caring ;)
 Re: “puppy belly,” I’m saying that blood isn’t rushing to the stomach and thus leaving limbs and brain relatively low on nutrients and/or oxygen. Separately, studies seem to indicate that most people on IF aren’t actually going into so-called “starvation mode.” To the extent IF may work, its efficacy is not predicated on this anyway.