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Time Restricted Eating/Intermittent Fasting

I've recently started doing this (3 weeks ago), I try to eat all my food in a 10-12 hour window and then fast for the remainder.

It's pretty easy to do but so far I've not seen any dramatic results in terms of weight loss or sleep improvements etc.

What I have seen is an enormous improvement in my cycling. I usually fit in a few 10-20 minute efforts on my longer rides and over the last 2 weeks I've managed to knock 30s-1m off my PBs for most of those that I attempt.

The first time it happened I wasn't even going hard, happened to glance at the Garmin and saw I was 15s up on my PB, pushed on at that point and ended up 45s ahead of a PB that had stood for 5 years.

My weight is about a kilo over where it normally is at this time of year and I'm on my winter bike which is 3 kilos heavier than the summer bike. My training has been identical too.

Weirdly my Strava fitness score (which I always thought was nonsense) is now at its highest ever level too despite no change in training compared to normal.

I read around and apparently it's a thing with TRE.

Anyone else had similar results?

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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25 comments

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JMcL_Ireland | 1 year ago
3 likes

I'll give you my perspective as I've been effectively doing a 16/8 - give or take - for about 5 years now,  with varying degrees of keto/low carb. Dinner is usually finished by 8pm, and I typically wouldn't have eaten until lunch anytime from 12-1:30 next day.

I'll start by saying I don't cycle competitively, just for fitness and enjoyment

I was initially interested in seeing how fasted training would go (I almost always head out on the bike early in the day), and started with 20km, building up to 30/40/50km with no ill effects. Probably the longest fasted spin I've had was in the 120-130km, 5 hour ballpark. Performance wise, I couldn't say I was any faster, though that may well be down to just getting older, but by and large endurance was good. I think I've only bonked badly once in that period - though can't remember the circumstances for that exactly.

Fast forward to today, and through a combination of getting demotivated by lockdowns and a couple of bouts of covid, my fitness fell off a cliff until the end of last year. Despite adhering to the 16/8 in general (though relaxing the keto) my weight also ballooned from 82kg in mid 2020 to 96kg just 2 months ago (this while following a TrainerRoad plan so pretty active). Since then I've taken it more in hand using MyFitnessPal to log calories with a daily deficit. MFP is handy as it links to Garmin Connect so any calories burned during workouts get synced and added to the daily total, which given that my cycling - be it indoor or outdoor - generally has both power and HR should be reasonably accurate. The result is I've shed about 5.5kg which is a good start (and got me up the mountain 2 weeks ago that beat me in April).

Having eliminated the low hanging fruit (more or less restricting booze to a glass or two at the weekend, not reaching for the bag of crisps at the end of the day), I was surprised how difficult it was to fill even a 500 daily calory deficit in 2 meals - I'd just end up feeling stuffed. I've started to eat a breakfast to pad that out and that's working fairly well. A result of that is that I'm eating a bit earlier in the day, but would still have a roughly 14 hour fast.

My Strava fitness level is also peaking at the moment, but that's probably more down to a couple of big rides in the last few weeks, as well as the TR plan reaching the end. So while I'm unconvinced that it'll make you faster (or me at any rate!), it should definitely help the endurance side. I did one of the recent rides - a 200km audax course - with a few mates with very little food intake on the road, certainly not enough for what was burned. They though I was mad. Now I did end up cramping badly in the last 25km, but I put that down to underdoing rehydration on what was a hot day.

So not really sure if that answers your questions, but it's insights from a reasonably long term perspective.

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simonmb | 1 year ago
1 like

Aim to get down to a 5-hour eating window and drop in a 24-hour fast when your riding/training schedule allows (at least 48 hours after a long ride and not less than 60 hours before your next long one). And DON'T fast every day. Shock your body by having breakfast at a 'normal' time once every couple of weeks, and eat three good meals that same day. Try to shift towards a keto intake too. It can work for cyclists, but it's not easy, and it's not fun. And probably isn't worth it for most folk. 

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Owd Big 'Ead | 1 year ago
3 likes

A 10 - 12 hour window for eating is hardly restictive, is it?

I'm presently doing a 16 - 8 plan, so no food for 16 hours and then an 8 hour window for eating and even that isn't anything out of the ordinary.

Lets not forget that it is the food industry's own "research" that has come up with the notion that we "must" have 3 meals a day in order not to wither and die. Just like the latest fad to market everything as being "high in proten" it's all bullshit.

I can't come up with any scientific reviews or peer reviewed studies to back up my anecdotal evidence, but I always ride stronger and faster when the weather warms up like it has ocer the last month or two. 

Are you sure that it's the change in eating patterns that's caused this significant uplift, or is it just circumstances falling into place?

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Rich_cb replied to Owd Big 'Ead | 1 year ago
1 like

16/8 is out of the ordinary, most people apparently have <10hrs a day of continuous fast.

Health benefits are apparently greater the longer you fast for but do start at the 12 hour mark.

It might well be circumstances, hence why I asked if anyone else had noticed a similar benefit from TRE.

As far as I can tell nothing else major has changed, I'm marginally heavier than normal, I'm on a heavier bike, doing my usual mileage and training and getting same amount of sleep. The change in performance on those short efforts has been quite significant and I'm struggling to think of what else might have caused it.

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HoldingOn replied to Rich_cb | 1 year ago
4 likes

I was always told muscle is heavier than fat, so perhaps it is simply that?

By the way, I did a quick Google to check that what I had been told wasn't a flat out lie and was presented with this nugget. Thank goodness "science" was on hand to clarify

 

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Rich_cb replied to HoldingOn | 1 year ago
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I'm not one to argue with science and my body composition may have changed resulting in the improved form.

If true, as my training, diet etc is otherwise unchanged it would suggest that the change in body composition was purely down to changing when I eat, which would be quite remarkable.

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HoldingOn replied to Rich_cb | 1 year ago
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I'd be interested to know if the trend continues.

I'm always looking for ways to improve.

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HoldingOn | 1 year ago
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I have never tried TRE, but I remember reading somewhere that our meals have become reversed. We would be better eating bigger meals at the start of the day, moving to a light evening meal. Something to do with starting the metabolism in the morning and having all day to burn through. It said our metabolism slowed during the night,so a big meal just before bed takes longer to go anywhere.
I know my extra weight comes from snacking during the evening. Not sure a reversed meal plan would stop that! TRE would though (assuming I don't set my window to be 1000-2200)

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Rich_cb replied to HoldingOn | 1 year ago
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I've been reading a book* about TRE, according to the book melatonin release in the late evening interferes with glucose metabolism and leads to larger blood sugar spikes and longer digestion times.

The book also mentions the idea of a bigger breakfast and smaller evening meal as being beneficial.

Apparently the endurance benefits come from an increased ability to metabolise ketones. Froome was a fan of fasted training for the same reasons and ketones are widely used by professional cyclists so perhaps there is something in it.

*Circadian Code by Satchin Panda

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Simon E replied to Rich_cb | 1 year ago
3 likes

Rich_cb wrote:

Apparently the endurance benefits come from an increased ability to metabolise ketones. Froome was a fan of fasted training for the same reasons and ketones are widely used by professional cyclists so perhaps there is something in it.

Many pro riders and coaches have been moving away from fasted training in recent years, except maybe for ultras. "Fuelling for the work required" is the current mantra, eating well beforehand and getting the calories in during exercise [CW]. But this is really for 2 hour+ rides, glycogen stores will be fine for shorter rides and commutes.

I've been commuting 40-60 mins on an empty stomach for 15 years. My 'sprightliness' or the absence of it (for want of a better term) varies and I think has more to do with time of year, temperature and weather, sleep and other life-related issues than whether I eat food before riding.

I'd not take the outcome of your recent experience as conclusive. If it works for you that's good but I'd be reluctant to hang my hat on this specific peg. I'd also not want to exaggerate the likely role of ketones. It may be that your food timing and activity levels the night before are playing a role; or could it be the cumulative effect of eating/living better over weeks, maybe even months?

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Rendel Harris replied to HoldingOn | 1 year ago
6 likes

It does sound interesting, the only problem for the middleaged real ale fan is that fitting one's daily pints in at 9AM tends to be frowned upon by employers, spouses and police officers...

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hawkinspeter replied to Rendel Harris | 1 year ago
4 likes

Rendel Harris wrote:

It does sound interesting, the only problem for the middleaged real ale fan is that fitting one's daily pints in at 9AM tends to be frowned upon by employers, spouses and police officers...

That's one of the benefits of "working" from home

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Rendel Harris replied to hawkinspeter | 1 year ago
1 like

hawkinspeter wrote:

That's one of the benefits of "working" from home

yes I wish - I've been freelancing from home for nearly twenty years so the employer and police officer problems don't come into it but the spousal disapproval still keeps me on the straight...

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HoldingOn replied to Rendel Harris | 1 year ago
2 likes

Rendel Harris wrote:

It does sound interesting, the only problem for the middleaged real ale fan is that fitting one's daily pints in at 9AM tends to be frowned upon by employers, spouses and police officers...

If you are drinking real ale until 2300, just start your day at 1100. Problem solved. Make sure the local real ale establishment is well lit though - keep that melatonin at bay.

@Rich_cb - I am going to have to look into that book. Sounds fascinating. I am a firm believer in routine, so my Circadian rhythm is of great interest to me. There are definitely days when I feel stronger than others (weirdly - some days I can feel strong cycling, but weak running and vice versa)

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Rendel Harris replied to HoldingOn | 1 year ago
6 likes

Whoa, so I can drink beer until 11PM, not get out of bed until nearly midday, and I'll still lose weight? This is the sort of training programme with which I can really get on board, much obliged!

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HoldingOn replied to Rendel Harris | 1 year ago
1 like

hmm I may have misunderstood TRE....

If I haven't though 

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CyclingInGawler replied to HoldingOn | 1 year ago
4 likes

The old adage suggests you should breakfast like a king, lunch like a prince, and have the dinner of a pauper. My parents were telling us that over 50 years ago (not that I took sufficient notice later in life!).

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Rich_cb | 1 year ago
1 like
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hawkinspeter replied to Rich_cb | 1 year ago
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Can't share any experience as I don't do any fasting though I could definitely do with dropping some weight.

It reminds me of the fasting rules of Ramadam - no food or drink (or swearing or sex) during sunrise and sunset. (Not that I'm muslim - just heard about it)

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Rich_cb replied to hawkinspeter | 1 year ago
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Yes it is similar but oppositely timed usually.

Ramadam involves fasting during daylight hours but most TRE schemes put the fast overnight.

Interestingly there is some data to suggest we metabolise food differently based on when we eat it. A sugary meal will produce lower blood glucose spikes in the morning than the evening for example so Ramadam style fasting may be less healthy than the usual TRE approach.

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Brauchsel replied to Rich_cb | 1 year ago
4 likes

Rich_cb wrote:

most TRE schemes put the fast overnight.

This is excellent news, I hardly ever eat in my sleep  

Rich_cb wrote:

Interestingly there is some data to suggest we metabolise food differently based on when we eat it. A sugary meal will produce lower blood glucose spikes in the morning than the evening

As a type 1 diabetic, the opposite is true. All breakfasts with any carbs, let alone actual sugar, spike my blood sugar vastly more than at any other time. Apparently I'm unusual in the size of the spikes, but it's common enough to be called the "dawn phenomenon". It's due to increased adrenalin to wake you up also restricting insulin efficiency. I'd be interested to know if the opposite is indeed true for those with a working pancreas, and if so why: it wasn't the sort of thing I used to think about when I had one...

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marmotte27 replied to Brauchsel | 1 year ago
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If you had a working pancreas once but not anymore, doesn't that make you a type 2 diabetic?

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mark1a replied to marmotte27 | 1 year ago
5 likes

marmotte27 wrote:

If you had a working pancreas once but not anymore, doesn't that make you a type 2 diabetic?

No; type 1, your pancreas is not producing any insulin at all, with type 2, you can be producing insulin, but either not enough, or your body has become resistant to it. Type 1 can happen at any time of life, often in youth and can be caused by a viral infection, auto-immune problem or is genetic. Type 2 is more often than not lifestyle related (although sometimes ethnic), where you stop breaking down glucose, eventually leading to the pancreas stopping insulin production. Complications and outcomes are usually similar in both types, retinopathy, neuropathy leading to eyesight and limb problems, not to mention liver & kidney problems, caused by the effects of excess glucose within the bloodstream. 

Type 1 is treated with insulin, with the additional risks of hypos (too low in sugar leading to drowsiness, fainting and worse), type 2 is treated with diet & exercise, weight control and often drugs to lower insulin resistance. Eventually with type 2, once the pancreas packs in, then it's insulin for that too. 

I have type 2 and cycling helps keep it under control.

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Brauchsel replied to marmotte27 | 1 year ago
3 likes

mark1a is correct. I had a working one for over 40 years, then all of a sudden I didn't. The medical explanation for its onset boils down to "just shit luck", essentially. 

On the plus side, my w/kg is better than it's ever been now I have to think rather carefully before eating anything. 

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Armchairanarchist replied to Brauchsel | 1 year ago
1 like
Brauchsel wrote:

On the plus side, my w/kg is better than it's ever been.....

I think having redundant organs removed is probably a bit of an extreme way to improve watts/kg, but I suppose marginal gains and all that........

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