No issues with not taking in nutrients for hours after your workouts? My thought was working out at 5am and then not eating until noon (or whenever you start your 8 hour eating window) you’re missing out on the most efficient time for replenishing gycogen. Also I’m curious how you handle longer endurance rides (like 3+ hours).
Works for me. On my two days off, I skip breakfast and eat after a 18 hour fast. However I cheat a little bit and take amino acids (no calories). My FTP has gone up steadily despite my age (53) and weight is constant at 65 kg (177cm).
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I train fasted in the morning as I have no time to eat before. I have found that I can hit all my numbers and my ftp has gone up despite my age. I eat well afterwards.
Same here, i wasn’t really talking about fasted rides in the morning, as anything under 90 minutes I can usually hit fine without any food, and I eat afterwards. It’s more about the workout landing smack dab in the middle of a 16 hour fasted period for people doing intermittent fasting. So fueling the workout aside, I’d think recovery would be impacted as you’re making your body wait an additional 6-8ish hours for any replenishment.
It seems to me the ideal schedule for that would be something like:
Fast until Noon, eat lunch, workout around 2 or 3pm, have some sort of recovery food, eat your last meal before 8pm. Repeat.
That way you’d have fuel for your workouts as well as recovery nutrition while maintaining your fasting periods. But I don’t know a lot of people who can squeeze in a 1-2 hour workout in the middle of the work-day.
From what I have seen, amino acids or BCAAs do both have calories. Due to FDA rules around labeling / supplements, protein content and calories do not need to be declared for products containing individual amino acids.
Ex: Valine is 6cal/g, Alanine is 4.3cal/g, etc. The base amino acids / BCAAs have calories, so the powder or pill should as well.
There are a variety of scientific studies on intermittent fasting from a health perspective. I do agree that the weight loss thing may not work for everyone, but for me it made a huge difference. And I would never recommend fasting to increase one’s performance, though I have anecdotally noticed some personal benefits with fasted training - specially faster recovery and less muscle soreness. The theory is that your body does not product lactate when processing ketones for muscular energy so it creates less soreness overall. This I am sure has not been scientifically proven but you can find hundreds of people online talking about their personal experiences.
The thing that is most interesting to me in the studies I read is basically how it teaches your cells to use ketones for energy. People that are always eating (never fasting) and always have glucose available to power their cells become very dependent upon this. If you take it away you force your cells to learn how to switch back and forth between glucose & ketones which makes them overall more flexible for a variety of things.
There’s also a growing belief that fasting and keto diets in general can be used as an alternative cancer treatment because the cancerous cells are normally built to be powered by glucose, so if you starve them of that and they don’t have any energy they die off, whilst the normal cells which are capable of using ketones can carry on.
To say there is no supporting science doesn’t sound very accurate to me.
Agreed. But the make-up of those calories plays a vital role too
I vital role in what? Weight loss is achieved through a calorie deficit.
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Sorry should’ve been more specific, my bad.
The body uses a lot more energy metabolising protein compared to fat. So therefore consuming more protein will increase the calorie out part of the equation
I agree totally with the CICO without doubt but you can increase your CO with clever nutrition
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My N=1 (supported anecdotally by other people I know who have played around with this stuff:
I’ve found intermittent fasting is great for losing or not gaining weight during periods when training is taking a bit of a back seat. E.g. when recovering from injury or illness, or when work or life stuff is just full on and you’ve put training on the back burner. At a minimum I’ve found it to be a very simple way of restricting calories without having to calorie count. I feel like there are other benefits in terms of energy levels (after an initial adaptation period), gut health, and simply learning to listen better to my body and distinguish between genuine hunger vs dehydration vs being bored at work and snacking out of habit. But weight loss/maintenance is the main reason I do this.
I’ve also found intermittent fasting to be completely incompatible with a high volume or performance-focused training plan. I simply can’t find a way of fuelling and recovering properly from the key workouts within the 16:8 schedule, always ends up impacting quality and/or recovery. Maybe that’s just a logistical challenge with my work and life schedule and other people can find a way of doing it, but for me it was an insurmountable hurdle.
What does seem to work well for me instead is targeted fasted rides within an overall high carb, high volume plan. I start most weeks now with a ~2 hour Z2 Monday morning pre-work ride done on nothing more than a quick double espresso before I go. Will try to have a low carb meal on Sunday night (not always successful…) and then refuel immediately after the ride. Will often do a further 1-2 fasted endurance/recovery rides during the rest of the week. Difficult to really quantify the benefit as those rides aren’t being done in isolation. But certainly don’t seem to be any downsides from a performance perspective and my overall body composition has improved since I introduced them. I think there may be some marginal gains in my ability to burn fat as fuel, as I’ve noticed I seem to fade less on long, hard rides when I am taking on carbs, but would be very hard to quantify the improvement, if any. For me personally it also seems to be a good way of cleaning the mind and body at the start of a new week, always feel good after these rides.
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Oxidative hierarchy of macros comes into play here - the order/timing in which the calorie are consumed is also important. @Charlie_Botterill’s point regarding thermic effect of foods could be important when assessing mass balances.
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Oh I love science 
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Who doesn’t!
Stick some acronyms in, link to a pubmed paper and it’s a win!
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During the week I find it very beneficial as a calorie control method. I’m a grazer and tend to eat all day long. IF works for that because it says “you can’t start eating until this hour”, plus, during the week I train in the afternoon, so I’ve had time to top up at lunch.
During the weekend, when I ride in the morning, it just doesn’t work. I’m a high carb rider, and I need those carbs!
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Couldn’t agree more 
Have a friend whose 8yo son has some very rare form of bone cancer and the specialist she is taking him to is talking about keto. Sure, n=1 but clearly there is something to this if oncologists are suggesting it as a treatment.
Cells grow and die quickly and there are trillions of cells in our bodies. One paper I read on the subject (which was based on a study done on mice) did show a behavior there of cellular adaptation with IF. Unfortunately I don’t have the study anymore - my brother who works for NIH sent it over as a PDF via email and I deleted it some time back. But here and here are a couple of studies which sound similar on mice and dogs.
The reality is that as a species we are nearly impossible to study from a scientific perspective when it relates to long term nutrition outcomes because enough people can’t stick to any diet for long enough in a controlled manner to properly conduct a study with sufficient scientific evidence to draw any hard conclusions. So studies on animals are the only thing we have to go on for real scientific conclusions.
That’s why that paper came out last year saying, despite all of the studies linking red meat consumption to cancer and poor health outcomes, you can really eat as much as you want, because none of the studies are actually convincing from a real science perspective. Can you name any study on long term nutrition from diet which establishes anything to have a health benefit and isn’t contradicted by ten other studies?
I read a while back about cancer and keto protocols. Certain types to cancers seem to feed on sugars. Other cancers don’t. I’m pretty sure I also read that fasting could improve the effect of chemo. Again, it was good for some kinds of cancer and some types of chemo.