Had a friend in university, he did military service for 1 year and the only thing he had for breakfast during that time was a strong black coffee without any sugar nor milk.

He screwed up his digestive tract for good - there is apparently something in coffee that is quite aggressive on stomach and gets neutralized when mixed with any sugar/milk/food. He will never be able to eat vast array of common foods - things like marmelades and other basic food. Sorry I don't have any further info, has been few years ago.

He might have some unique predisposition for this, don't know, but better be careful and put at least some milk in it. It makes it much more filling anyway

For another anecdote, I have been drinking black coffee, and only black coffee, for the first four to six hours of the day. Sometimes water as well.

I have done this for about six years without damaging my digestion in any detectable way. I would bet money your friend has or had a Helicobacter pylori infection; treatment is antibiotics.

I tried the same for for about 6 months but had to stop because of stomach ache. I'm not infected with helicobacter pylori.

Sure, people differ greatly in acid sensitivity and other factors that make no one diet right for everyone.

The stomach ache went away when you quit? If not... are you sure you don't have helicobacter pylori?

Yes it went away and yes I was tested multiple times for helicobacter pylori.

That definitely sounds like some predisposition. The whole idea around intermittent fasting revolves around eating in a specific time window, outside of that you don't consume any calories at all. Many people I know of do this, in order to lose some weight or gain muscles without adding too much fat, never heard of this problem.

Coffee can be quite acidic which with people with overactive stomachs can cause issues such as acid reflex, ulcer etc.

Instant coffee tends not to be as acidic same goes for cold brews and there are other ways to neutralize the acidity.

If you produce too much acid then intermediate fasting is not a good idea to begin with unless you also take supplements to control your stomach acidity.

FWIW I used to get heartburn pretty regularly and that has completely gone away since I switched to a plant-based diet.

Not everyone can take coffee (or tea for that matter) on an empty stomach. And of course there are many levels of "strong".

The other large confound is he was in the military service during this time. And stress can totally mess up the GI tract.

I used this quite consistently to drop about 10kg (gradually but quite steadily) to compete in weight-class sporting events. It was really easy as compared to most other methods of weight control.

Lunch->dinner may not be as ideal from the circadian rhythms approach (as per the article) as breakfast->late lunch, but it's sure easier on family/social life.

I've skipped breakfast for years and my body is not missing it.

That said breakfast may be important when doing intermittent fasting for losing weight, because the secret there is to not let your metabolism get used to a certain rhythm, or in other words it's best if you are little unpredictable in what meals you eat or skip — so when doing IF, in some days I eat breakfast and skip dinner.

And when eating dinner it's best if you eat light, b/c digestion during the night sleep can make you tired during the next day. My general rule is to eat about half what I ate for lunch.

This is ridiculous - the point of choosing a predetermined window for feeding is so your body adapts to only expecting food within that window. Routine is incredibly important for being able to stick to something like IF. If you're fighting your body at every step by, for example, being unpredictable, you're just screwing yourself.

This seems unlikely in evolutionary terms. It's more likely that eating times were unpredictable for most of our history and that our bodies have evolved to prepare for digestion based on external stimuli such as sight and smell of food.

This is completely unsubstantiated. Worse yet, the "from an evolutionary standpoint" trope is frequently (ab)used to support some kind of pseudoscientific idea/diet (Paleo springs to mind here). If you have a real, coherent argument based on verifiable truth to make that is great, but right now you're just making something up and running with it because it feels right to you. Nobody benefits in this scenario, least of all you.

Please read my comment again and pay attention to the language I used. I'm expressing an opinion, not writing a thesis.

The difference between us back then and us now is context. We live in an age of complete overwhelming external stimulus. You see food or calorie-laden drinks everywhere you look. The point of routine, which is also an evolutionary trait, is to reduce reliance on willpower and avoid wasting energy on making decisions. These are real problems that we have right now because of our body's greedy, opportunistic behavior (which was evolutionarily advantageous when food wasn't so abundant and also had completely different forms).

Why would unpredictability be good? If you eat at the same time your body starts preparing to digest the food before you eat it, making for a faster, better digestion of the food.

Just to speak to the contrary, I’ve been using 16:8 for a few months, simply because the evidence for the health benefits of short fasting seems reasonable, and anyway it’s stopped me late night snacking.

One downside is that immediately after lunch I find myself very very drowsy. Sufficiently so that on some days I have to disappear into a meeting room for 10 minutes for a nap.

> Sufficiently so that on some days I have to disappear into a meeting room for 10 minutes for a nap.

Pretty common in some European countries and there are plenty of studies showing the positive benefits of "power napping". Shame it's so frowned upon where I'm from (UK).

I'm sure nobody would mind you using 10 minutes of your own time to have a quick nap?

Going home for 3 hours isn't really the same thing.

I had the same problem. I used to think that drinking a cup of coffee after lunch would help, and it did, but after a few months it stopped being effective and only made it harder to fall asleep in later in the evening. However, about a month ago I started aggressively fixing my sleep schedule and stopped consuming any coffee, and I now don't experience these drowsy after lunch periods at all.

What do you typically eat for lunch?

Taking a short nap might not necessarily be a bad thing I think. I usually take a 10-20 minute nap in the afternoon if I can.

> One downside is that immediately after lunch I find myself very very drowsy.

What does a typical lunch consist of for you?

Same for me, usually fixed with a cappuccino or a caffeine tablet though

Different people have different needs. My brother could skip breakfast at will since he was a kid; I would go on a murder spree without my morning food. He never craved carbs in the same way I did, and has a very different body structure.

For the record, there are other ways to do IF: I am pretty happy skipping lunch, because eating mid-day makes me sleepy and slow anyway.

I also would go on a murder spree without my morning food. But then I stopped eating breakfast and ... it worked.

Here's what I did:

   1. Make sure you eat late in the evening (I like to eat a snack at 11pm or later)
   2. Lower your carb intake
   3. Up your protein intake
   4. Up your fats
   5. Generally have a large dinner instead of a large lunch

I shifted my schedule because I work out in the evening and it makes sense to eat a large meal afterwards. Helps you recover. And I eat late at night because I usually go to bed between 2am and 3am. Need energy.

Part of this shifting schedule was that I gradually reduced the size of my breakfast and eventually removed it. In the mornings I'm not doing anything physically demanding so I don't need that much energy and my large evening intake is still good enough.

That said, I always wake up with a growling stomach and sometimes even hunger pains. They go away after I have some morning tea (warm liquid) and my body generally forgets its hungry if I make it wait like 20 or 30 minutes before I give in.

As a bonus, my bodyfat percentage has gone down to a stable 11% while maintaining the same weight.

Oh yeah, I also drink 2 to 3 cans of Coke Zero per day to help with my sodium intake. Especially with the amount of working out I do I get leg cramps when I forego soda.

> Oh yeah, I also drink 2 to 3 cans of Coke Zero per day to help with my sodium intake.

Not true. The 40mg of sodium in a can of coke zero isn’t enough to offset the liquid in the coke.

When I’m fasting I try and get 7 full grams of table salt daily. I’d wager the coke zero is actually desalinating you.

If you’re cramping at all, you need a LOT more salt. Also likely porassium and magnesium.

Your body’s hormones control your salinity levels on a much vaster timescale than your daily, or even weekly, dietary intake.

Source - https://www.nih.gov/news-events/nih-research-matters/how-bod...

Maybe it’s placebo, then. Whatever it is I’ve noticed a clear connection between cutting coke and cramps coming back.

Of course my experiment wasn’t super rigorous and double blind so it could be completely wrong. It’s hard to know. But when it comes to body stuff I find it’s usually best not to overthink. If something works for you, keep doing it. Every once in a while try removing stuff you do to see if there’s an effect.

Before I started doing this I also would have a hard time doing without breakfast. And even with breakfast if I had a strong cup of coffee I would get shaky and lightheaded. So it seemed counter-intuitive to me that eating nothing at all would be better but it's worked out that way.

Not saying that's true for you but I thought I couldn't go without breakfast until I actually tried it.

I skip breakfast, lunch, and have a 3 hour window for eating in the evening. I have more energy during the day, clearer thinking, and dropped some pounds.

First meal of the 3 hour window is non-carbs - lean protein, greens. last 1.5 hour of window I do carbs

Consuming 2000+ calories in a 3 hour window is pretty hard to achieve I've tried it and man is it though.

On a 23:1 cycle, I have to be careful w/ the way I resume eating. Start with heavy foods and I'll be in the bathroom very soon.