Yeah I always joke that "intermittent fasting" is really just fancy jargon for "skipping breakfast" - at least it is for me. Don't eat till noon, don't eat after 8pm - congrats, you're part of the IF crowd.

And yes, it does seem to help burn a bit more fat than before - though I wouldn't call it life-changing.

These are the basics, yes, but it's not that simple. To me, IF means: from 8PM to noon next day drink only water and (if you like) one black coffee in the morning. Then, from noon until 4PM eat just proteins, healthy oils & fats and raw vegetables - this is crucial, absoultely no carbs! Finally, from 4PM until 8PM eat everything.

That way you keep insulin under control for the 20 hours (out of 24). Your concentration and focus will increase very soon.

Why only one cup of coffee? Is it the caffiene? Does decaf apply here too? (I work in coffee and often skip breakfast.)

Good question! I'm sorry I left out the details. Yes, it is the caffeine and the book I followed (The Renegade Diet by Jason Ferrugia) recommends 1 cup about 30-45 mins before the workout to burn fat even faster.

Even though I now rarely work out before going to work, I still start my day by drinking a glass of water and then a cup of coffee and it still feels good :) If you drink decaf, I think it would have no positive (but probably also no negative) effect.

I've been practicing IF for over 3 years now.

It hasn't been life changing in itself, but I found it to be beneficial for keeping my body weight stable, which in turn improves a bunch of other health outcomes. It could just be placebo, but I feel much better with IF.

Does it really work? I don't know, the scientific evidence isn't that strong at the moment.

But it has convex outcomes: if it works, the upside is tangible... and if it doesn't, the downside is negligible.

Going on two years of 16/8 IF myself, but I'd say that it absolutely was life-changing for me.

I initially lost about 45 lbs (217 – 172) in about 10 months, but have since leveled out between 170-175. Beyond the weight loss, I noticed marked improvements in general energy levels, sleep quality, and chronic issues such as heartburn. More importantly though, I think the biggest adjustment that IF enabled me to make was transitioning into _wanting_ to eat healthy/whole foods and cut out foods with processed carbs and added sugar.

But I totally agree, there definitely is a psychological aspect of it, whether the improvements are quantifiable or not. Maybe the results are placebo, maybe it's confirmation bias, but I definitely think that IF allowed me to reframe the way I approach my diet, and eat in a way that is more attuned to being healthy.

Huh, I've been doing this for years without realizing it. I'm never hungry in the morning except for coffee (maybe that ruins this). To add more to discussion I also lift 4-5 times a week. Besides obvious physical benefits of muscle mass lifting improves life in many other ways. I notice if I ever skip or don't stick to my regular gym regimen I mentally feel unfit. Going to the gym actually increases energy and allows more productivity at work, social outings, etc.

If you look at Rhonda Patrick's work, she does the reverse: time restricted eating. It's the same thing, you give yourself 8-9 hour time window to eat (instead of having a 16 hour fasting window). I think she recommends skipping dinner though because she's all about the circadian rhythm and eating only when it's light out. But I don't think she has any scientific reasoning behind that.

She's also not a fan of drinking coffee during your fasting period, and she believes that breaks the fast because the liver metabolizes the caffeine. So that starts the metabolic process in the body, taking you out of the fasted state.

Most people skip breakfast, like I do. It's easier for busy people to skip breakfast. I think it depends on the person's schedule. I skipped breakfast before and tried skipping dinner. Both methods work well. Skipping dinner does make me bored at night. I had all this free time not having to cook or eat. That could be an advantage for some people.

Breakfast isn't that important. Nutrient timing is mostly made up junk science. Eating some carbs after cardio is important. But, generally, it just doesn't matter too much. IF, I do still like to eat before or after a workout and then fast. Or just do regular old 24h fasts. It's 100% mentality once you get used to it.

> Eating some carbs after cardio is important.

Why?

Your body is replenishing glycogen stores in your muscles and that happens much faster if carbs are consumed shortly after exercise.

If you're in ketosis before exercising, your body doesn't have those glycogen stores to begin with, right?

That's right. You basically won't be able to do a cardio effort to your body's capabilities. Anyone that has ever run an ultra marathon is essentially operating in ketosis like state. You just burn more energy than your body can absorb so it is a combination of stored fat and incoming carbs/fat/protein that keep you moving.

edit: Your body also slows down its nutrient absorption rate during any exercise as it diverts blood to your extremities and core body functions. So digestion is more of a challenge.

Carbs are absolutely /not/ required for long-duration cardio. There are high-performing, low-carb, cardio athletes. For example: (first link off a google esarch) https://www.mensjournal.com/health-fitness/zach-bitter-100-m...

Studies that show a drop in cardio performance from low-carb have been measuring in the adaptation period, before the body adapts to low-carb performance.

This is covered pretty thoroughly and with a much higher level of detail in Lore of Running (Noakes). Down to the biochemical level of what is actually going on as you adapt to a low / no-carb state. You have to be precise with what you mean by "long-duration" cardio. Up to Marathon level you simply won't be able to go as fast as a runner that has muscle glycogen. You won't find any examples of elite marathon runners performing at their peak on a no-carb diet. Somewhere right at, or shortly after, marathon distance for most runners you have used up your glycogen stores anyway, so a great portion of your ultra is going to be executed without a lot of carbs / easy glycogen anyway. I don't think anyone will dispute some runners can operate with no carbs, etc. So, it just makes sense to train your body to burn fats / body fat efficiently because that is where a big portion of your fuel comes from in an ultra.

I can't remember the exact time period, but it only takes a few weeks to fully adapt to low/no carb diet where your body gets good at making energy from fat. The actual chemical process is really cool.

You definitely lose your ability to do high performance shorter events at the peak of your body's capability (5K/10K, etc.). It is simply a less efficient process of creating the primary fuel your cells use to do their thing.

You also have to be precise about what you mean by "elite". Definitely "most runners" don't fit that category, so saying "you simply won't be able to go as fast" is probably overgeneralizing.

https://www.theguardian.com/lifeandstyle/the-running-blog/20...

“If you’re going to run a marathon under two hours and 10 minutes, then yes, you probably need lots of carbohydrate to be able to perform to such an intense level of activity, but once you’re slower than two and a half hours, I’m not really convinced you do.”

Adaptation periods are probably 6 weeks, possibly longer to fully adapt, though adaptation appears progressive.

And training low-carb can have benefits even if racing carb-loaded.

My understanding, barring real genetic outliers, is that the human body just can't go as fast in a fat adapted state. I would say "any runner". Meaning anyone with a few months of real training under their belt is going to run sub marathon efforts slower. The article you linked pointed that out. This isn't just for elites, but everyone. Most recreational/non-professional runners run sub marathon races. This implies some important things about how you train and eat. 1.) When doing max effort running, to push your body to it's limit you need some carbs. 2.) To run your fastest race you need some carbs. You can still train and do well without them, of course. I think for most runners it's fine and the difference doesn't amount to much in practical sense.

Here's an article that talks about the process of fat adaptation. https://medium.com/@davidludwigmd/adapting-to-fat-on-a-low-c... Note the graphs showing ketone levels continuing to rise through 38 days of complete fasting. If you are ingesting some carbohydrates or protein, this would slow the adaptation process beyond that.

There are lots of studies showing a performance decrease during within those early few weeks of the adapatation process, but they aren't really showing the fully adapted, optimized state.

I've read that high level body builders will actually eat candy after a workout for the same effect. Also, ultra marathons will have mountain dew at aid stations for that immediate boost.

If I understand completely, glycogen depletion is "the wall" that is referred to by cyclists as well.

Yeah there is interesting "math" you can do. But, for most people, your liver stores about 1200-1500 calories of glycogen. You have some in all of your muscles, etc. Marathon is right at the distance you can run and stay under "the wall". In fact, that is a key part of pacing. Finding your race pace to basically operate on glycogen for all but the last bit of it (1-2 miles) where you can just push/suffer through on will power. If you go out too hard, you burn glycogen too fast, hit the wall at 6 miles out... that is the suck. 6 miles can be an actual eternity when you hit the wall.

Only if you feel you need to "replenish glycogen stores". If you intend to remain in ketosis, you don't need to re-stock with carbs.

However, when your glycogen stores are depleted, your body is more able to make effective use of consumed carbohydrates (storing them in muscles), so shortly after exercise is probably the best time to eat carbs.

But it's really easy to go overboard.

Another approach that some people might prefer is a 24h once a week fast, which I've found much easier than 12-16h daily.

I don't eat breakfast per se, just a protein shake but I found it difficult to cut out for a number of reasons.

A couple of months ago my wife and I started doing a weekly 24h fast on Sundays from breakfast Sunday to breakfast Monday. The first couple of times it was a bit of struggle but now we don't really notice anymore.

Whatever fits your lifestyle is the way to go, otherwise it's always going to be a struggle to maintain.

So you don't eat anything at all for the whole day? Or is it something like nuts?

What about dairy products (like milk) etc?

No calories at all, just drink water when we're thirsty.

I've found it has worked wonders for resetting my relationship with hunger; I feel I'm far less susceptible to boredom hunger in the few days immediately after the fast, something I'm hoping will progressively improve further.

Honestly, we haven't found it that hard at all. The first two weeks were a bit of a struggle just because you aren't used to going that long without food, but now it's just the day we don't eat and we don't really pay it much attention past that.

I basically eat during work. That's it. Not before office hours and not after. Makes it very simple to track and routine-ize.

I do the opposite: dinner time to a bit before bed-time. Easy routine, no gross co-worker lunch smells, and I'm always eating planned meals I prepare. Better a hot steak than something reheated at work, IME.

I started experimenting with IF about a month ago. My experience has been:

- No obvious impact on rate of weight loss.

- I do seem to be getting better sleep at night.

I've been doing 16 hour IF for years completely unintentionally. I skip breakfast, lunch at 1pm, dinner at 8pm.

So I guess it's a habit thing. Once you make a habit of it, you just stick to it.

I only eat from 4pm to midnight (wife hates it if we don't have dinner together), and it's not a problem to last till 4 on back coffee alone if you tend to sleep late