IF for active people?

amandaeve · January 2020

After reading this article I'm tempted to try IF: https://www.nbcnews.com/news/amp/ncna1107836?__twitter_impression=true&fbclid=IwAR1miweST02UkY1onGW5jMXulVMGTNTmchA9ojDb2OUJ77pdmC2XVokMEi0

I could probably restrict eating for a block of hours a day and see what happens. I just can't decide when to start.

I workout from 5:45-7:45am (cardio and strength) and from 5-6pm (biking home from work) weekdays. I go to bed at 9:30 and wake up at 5:20am.

Any thoughts on the best time to fast and still fuel my activities in the healthiest way?

H_Ock12 · January 2020

How long do you plan to fast? If you're doing OMAD, I found the best time to eat my meal was in the evening, regardless of when I worked out...I found better quality sleep when I had a full stomach.

If you're doing a time block, I would personally focus later in the day...maybe late lunch and dinner after you bike home from work. I think it's personal preference...I generally have no appetite immediately after working out and often work out/run faster, so my preference was later eating window.

amandaeve · January 2020

Right now I eat every 2-3 hours, so I figured I'd start fasting for 12 hours and then try to build from there. OMAD never occurred to me. How would I do my weekend bike rides? I go out for 4-5 hours and I have it drilled in my head to fuel every hour on long rides.

sijomial · January 2020

amandaeve wrote: »

Right now I eat every 2-3 hours, so I figured I'd start fasting for 12 hours and then try to build from there. OMAD never occurred to me. How would I do my weekend bike rides? I go out for 4-5 hours and I have it drilled in my head to fuel every hour on long rides.

Two questions for you from a fellow long distance cyclist:

How many hours do you think you can ride before you deplete your glycogen and bonk?

What advantage do you think time restricted feeding will provide to you?

amandaeve · January 2020

The article promises:
"Studies in humans show intermittent-fasting helps reduce obesity, insulin resistance, high cholesterol, high blood pressure and inflammation. It can improve verbal memory, executive function and global cognition in adults with mild cognitive impairment." Sounds good to me (read with several coats of skepticism).

With a big meal the day before, I could easily go several hours without bonking. But the bonk could happen in the middle of my work day, too, which would be bad. And I'm not sure how far I could go without bonking if I made this drastic change in eating frequency.

Nony_Mouse · January 2020

amandaeve wrote: »

The article promises:
"Studies in humans show intermittent-fasting helps reduce obesity, insulin resistance, high cholesterol, high blood pressure and inflammation. It can improve verbal memory, executive function and global cognition in adults with mild cognitive impairment." Sounds good to me (read with several coats of skepticism).

With a big meal the day before, I could easily go several hours without bonking. But the bonk could happen in the middle of my work day, too, which would be bad. And I'm not sure how far I could go without bonking if I made this drastic change in eating frequency.

The first five of those things happen just with weight loss. Note that the ones around memory and cognitive function are in adults with mild cognitive impairment.

IF works great for some people for weight loss, but only because it helps them to stay within their calorie allowance. You still need to be at an overall deficit, and that isn't automatic, as the article seems to imply (I'm not a morning eater, and can easily eat beyond my calorie needs in an eight hour window or less, even focusing on nutrient-dense whole foods). Beyond that, it has no advantage for weight loss.

sijomial · January 2020

amandaeve wrote: »

The article promises:
"Studies in humans show intermittent-fasting helps reduce obesity, insulin resistance, high cholesterol, high blood pressure and inflammation. It can improve verbal memory, executive function and global cognition in adults with mild cognitive impairment." Sounds good to me (read with several coats of skepticism).

With a big meal the day before, I could easily go several hours without bonking. But the bonk could happen in the middle of my work day, too, which would be bad. And I'm not sure how far I could go without bonking if I made this drastic change in eating frequency.

Suggest you read the studies rather than just accept at face value someone else's interpretation - especially a journalist.
There's an awful lot of cherry picking of studies that support a hypothesis while ignoring those studies that suggest the opposite. Really evaluate those studies about how relevant they are to you (not someone else or even a lab rat!). Are you obese? Do you have insulin resistance? Do you have negative levels of inflammation etc. etc.

Deliberately go looking for the opposing view to get a rounded view - then make your decision which might just be very reasonably to experiment and see how if works out for you. (Carry a carb gel as an insurance policy wouldn't be a bad idea.)
Maybe even consider what elite cyclists and race teams do do with all their dedicated sports nutritionists and why they do it the way they do?

Bonking to a degree is a matter of maths.
Off the top of my head I think you can store about 15g of glycogen per kg of bodyweight (check for yourself to verify - I'm no more reliable than other voices on the internet!).
After a VO2 max test in a sports science lab I know the point at which I'm burning 50/50 carbs and fat for fuel so can work out when bonking is a danger.
But that 50/50 point is a pretty low level of effort (an all day event not a 4hr event if you like) - when performance/speed is my goal I'm burning through my glycogen at a much higher rate than that. Plus the issue that performance declines and fatigue increases before you bonk.
Believe me from personal experience bonking while riding on the road isn't just inconvenient, it's very dangerous. I was so confused I cycled past a load of shops where I could have refuelled and even forgot to unclip when I stopped at a junction. That's funny, I appear to have fallen over.....

A fat adapted athlete can change those carb/fat numbers to a degree - but at what cost in performance? Again that's personal - is your goal to complete a distance or to compete or complete a distance quickly?

My longest recent ride completely unfuelled was 40 miles and I felt fine but that was fully carb loaded and at a brisk but not fast pace. If I was trying to do that 40 miles fast I would definitely have added some carbs to my drinks - maybe I would have needed them, maybe not

chandraminick · January 2020

You could go keto to get fat adapted, and then you would be using ketones for your rides instead of glucose and wouldn't need to eat every three hours. If you're to thin to do keto, you could use exogenous ketones before the ride or during.

PAV8888 · January 2020

chandraminick wrote: »

You could go keto to get fat adapted, and then you would be using ketones for your rides instead of glucose and wouldn't need to eat every three hours. If you're to thin to do keto, you could use exogenous ketones before the ride or during.

Too thin to do keto?

What does thick-ness or thin-ness have to do with whether you eat keto, or South Beach, or vegan, or Paleo, or Mediterranean, or random way of eating? You can gain or lose weight with pretty much any way of eating and enough effort!

For athletic performance I would assume that any method that is favoured by the majority of athletes will work.

I think that most athletes tend to time their food intake for maximum energy availability and recovery subject to tummy and bathroom constraints!

<Disclaimer: not an athlete; but, I do fuel up my hikes!>

amandaeve · January 2020

sijomial wrote: »

amandaeve wrote: »

The article promises:
"Studies in humans show intermittent-fasting helps reduce obesity, insulin resistance, high cholesterol, high blood pressure and inflammation. It can improve verbal memory, executive function and global cognition in adults with mild cognitive impairment." Sounds good to me (read with several coats of skepticism).

With a big meal the day before, I could easily go several hours without bonking. But the bonk could happen in the middle of my work day, too, which would be bad. And I'm not sure how far I could go without bonking if I made this drastic change in eating frequency.

Suggest you read the studies rather than just accept at face value someone else's interpretation - especially a journalist.
There's an awful lot of cherry picking of studies that support a hypothesis while ignoring those studies that suggest the opposite. Really evaluate those studies about how relevant they are to you (not someone else or even a lab rat!). Are you obese? Do you have insulin resistance? Do you have negative levels of inflammation etc. etc.

Deliberately go looking for the opposing view to get a rounded view - then make your decision which might just be very reasonably to experiment and see how if works out for you. (Carry a carb gel as an insurance policy wouldn't be a bad idea.)
Maybe even consider what elite cyclists and race teams do do with all their dedicated sports nutritionists and why they do it the way they do?

Bonking to a degree is a matter of maths.
Off the top of my head I think you can store about 15g of glycogen per kg of bodyweight (check for yourself to verify - I'm no more reliable than other voices on the internet!).
After a VO2 max test in a sports science lab I know the point at which I'm burning 50/50 carbs and fat for fuel so can work out when bonking is a danger.
But that 50/50 point is a pretty low level of effort (an all day event not a 4hr event if you like) - when performance/speed is my goal I'm burning through my glycogen at a much higher rate than that. Plus the issue that performance declines and fatigue increases before you bonk.
Believe me from personal experience bonking while riding on the road isn't just inconvenient, it's very dangerous. I was so confused I cycled past a load of shops where I could have refuelled and even forgot to unclip when I stopped at a junction. That's funny, I appear to have fallen over.....

A fat adapted athlete can change those carb/fat numbers to a degree - but at what cost in performance? Again that's personal - is your goal to complete a distance or to compete or complete a distance quickly?

My longest recent ride completely unfuelled was 40 miles and I felt fine but that was fully carb loaded and at a brisk but not fast pace. If I was trying to do that 40 miles fast I would definitely have added some carbs to my drinks - maybe I would have needed them, maybe not

I have a lab tested vo2 max, but don't know when I'm burning what. Can you tell me the math for that?

amandaeve · January 2020

chandraminick wrote: »

You could go keto to get fat adapted, and then you would be using ketones for your rides instead of glucose and wouldn't need to eat every three hours. If you're to thin to do keto, you could use exogenous ketones before the ride or during.

I hear about fat adapted endurance athletes, but no way will I ever go keto. That would require too much suffering on my part. Plus I'm still not convinced ketosis is healthy for the average bear.

Azdak · January 2020

amandaeve wrote: »

After reading this article I'm tempted to try IF: https://www.nbcnews.com/news/amp/ncna1107836?__twitter_impression=true&fbclid=IwAR1miweST02UkY1onGW5jMXulVMGTNTmchA9ojDb2OUJ77pdmC2XVokMEi0

I could probably restrict eating for a block of hours a day and see what happens. I just can't decide when to start.

I workout from 5:45-7:45am (cardio and strength) and from 5-6pm (biking home from work) weekdays. I go to bed at 9:30 and wake up at 5:20am.

Any thoughts on the best time to fast and still fuel my activities in the healthiest way?

You are probably already doing that. I know that IF has gone into uberbuzzhype mode the last couple of weeks, but I still don’t think the evidence shows that it is something that everyone should do.

Azdak · January 2020

amandaeve wrote: »

sijomial wrote: »

amandaeve wrote: »

The article promises:
"Studies in humans show intermittent-fasting helps reduce obesity, insulin resistance, high cholesterol, high blood pressure and inflammation. It can improve verbal memory, executive function and global cognition in adults with mild cognitive impairment." Sounds good to me (read with several coats of skepticism).

With a big meal the day before, I could easily go several hours without bonking. But the bonk could happen in the middle of my work day, too, which would be bad. And I'm not sure how far I could go without bonking if I made this drastic change in eating frequency.

Suggest you read the studies rather than just accept at face value someone else's interpretation - especially a journalist.
There's an awful lot of cherry picking of studies that support a hypothesis while ignoring those studies that suggest the opposite. Really evaluate those studies about how relevant they are to you (not someone else or even a lab rat!). Are you obese? Do you have insulin resistance? Do you have negative levels of inflammation etc. etc.

Deliberately go looking for the opposing view to get a rounded view - then make your decision which might just be very reasonably to experiment and see how if works out for you. (Carry a carb gel as an insurance policy wouldn't be a bad idea.)
Maybe even consider what elite cyclists and race teams do do with all their dedicated sports nutritionists and why they do it the way they do?

Bonking to a degree is a matter of maths.
Off the top of my head I think you can store about 15g of glycogen per kg of bodyweight (check for yourself to verify - I'm no more reliable than other voices on the internet!).
After a VO2 max test in a sports science lab I know the point at which I'm burning 50/50 carbs and fat for fuel so can work out when bonking is a danger.
But that 50/50 point is a pretty low level of effort (an all day event not a 4hr event if you like) - when performance/speed is my goal I'm burning through my glycogen at a much higher rate than that. Plus the issue that performance declines and fatigue increases before you bonk.
Believe me from personal experience bonking while riding on the road isn't just inconvenient, it's very dangerous. I was so confused I cycled past a load of shops where I could have refuelled and even forgot to unclip when I stopped at a junction. That's funny, I appear to have fallen over.....

A fat adapted athlete can change those carb/fat numbers to a degree - but at what cost in performance? Again that's personal - is your goal to complete a distance or to compete or complete a distance quickly?

My longest recent ride completely unfuelled was 40 miles and I felt fine but that was fully carb loaded and at a brisk but not fast pace. If I was trying to do that 40 miles fast I would definitely have added some carbs to my drinks - maybe I would have needed them, maybe not

I have a lab tested vo2 max, but don't know when I'm burning what. Can you tell me the math for that?

If you have a lab tested VO2 max, the second thing they should have gone over with you (after they told you your VO2max) was your RER ratios at different levels of effort.

RER is respiratory exchange ratio. — it is the ratio of CO2 produced compared to O2 used. It is directly affected by the blend of carbs and fats being used for fuel.

The higher the RER, the higher the percentage of carbs used as fuel. The RER at rest is about 0.70. That is when we use the highest percentage of fat as fuel. An RER of 1.0 means that carbohydrate is the predominant fuel.

Once carbohydrate becomes the predominant substrate, it indicates an intensity at which performance is peaking, but endurance will start to decline. (I can’t remember the exact RER number —it may be 0.90–for that threshold). The intensity where that starts to shift is generally 62%-67% of VO2 max.

It is in the interests of an endurance athlete to push that threshold out as far as possible. For example, if one can remain in a relatively higher % of fat as fuel at say 70% of VO2 max, that will allow a higher level of performance at a glycogen-sparing intensity.

There are limits to how far you can do on the “fat adapted” path. At higher intensities, the body cannot produce sufficient energy via beta oxidation (that’s the process of fat metabolism) to meet the metabolic demand.

But, back to your original question. I don’t know how you were tested, but there should be a printout somewhere that shows your raw data. Usually results are printed at least minute by minute and include HR, VO2, and RER, among other things.

One of the disappointments of my career was that I never had access to metabolic testing equipment. I only underwent metabolic testing once after graduate school—that was about 8 years ago and the person screwed it up, so I never did get to actual max effort.

Lillymoo01 · January 2020

I am an early riser and like to start the day by walking for an hour or two before breakfast. I can not go more than 2 hours before a need to eat and there is no way I'd cope until lunch without bonking. I am also the type of person who can't sleep if I don't have a nice full belly which means that fasting at the end of the day would also be out of the question.

No one can really answer your question as we are all different and our body responds differently to meal timing. The best thing to do it try it out and see how you go. It won't take long to work out what meal timing scenario will best suit your lifestyle and goals. Just don't get too bogged down with apparent rules you have read about online. If it works for you then go with it. If it doesn't then don't. There is no instruction book that will suit everyone.

LoveyChar · January 2020

amandaeve wrote: »

The article promises:
"Studies in humans show intermittent-fasting helps reduce obesity, insulin resistance, high cholesterol, high blood pressure and inflammation. It can improve verbal memory, executive function and global cognition in adults with mild cognitive impairment." Sounds good to me (read with several coats of skepticism).

With a big meal the day before, I could easily go several hours without bonking. But the bonk could happen in the middle of my work day, too, which would be bad. And I'm not sure how far I could go without bonking if I made this drastic change in eating frequency.

For all of these reasons, I fast! I feel great when i fast and I feel that it helps me to maintain my healthy weight. I run. In 6 weeks, I'm running a marathon. So I had a physical done, vitamins and minerals checked and so forth and it was all great! I find that people who bring up this topic often become discouraged because there are so many cynics of IF. IF requires self discipline and restraint. I would not pay much attention to or put any stock in what people in these communities say or think about IF. You are smart to read the research done by medical professionals and then try IF for yourself and see if it works for you.

Orphia · January 2020

amandaeve wrote: »

After reading this article I'm tempted to try IF: https://www.nbcnews.com/news/amp/ncna1107836?__twitter_impression=true&fbclid=IwAR1miweST02UkY1onGW5jMXulVMGTNTmchA9ojDb2OUJ77pdmC2XVokMEi0

I could probably restrict eating for a block of hours a day and see what happens. I just can't decide when to start.

I workout from 5:45-7:45am (cardio and strength) and from 5-6pm (biking home from work) weekdays. I go to bed at 9:30 and wake up at 5:20am.

Any thoughts on the best time to fast and still fuel my activities in the healthiest way?

What are you hoping to achieve by making such a change?

How long have you been cycling?

Knowing athletes, and being one, it can be illogical to think that making major changes will help us make minor improvements.

I tend to think eating and training sustainably and letting the consistent training do the physical improvements for us is how we improve performance.

Regular easy endurance, a bit of speed, hills/effort, tempo and variety are how our physiology improves our metabolism.

Azdak wrote: »

amandaeve wrote: »

sijomial wrote: »

amandaeve wrote: »

The article promises:
"Studies in humans show intermittent-fasting helps reduce obesity, insulin resistance, high cholesterol, high blood pressure and inflammation. It can improve verbal memory, executive function and global cognition in adults with mild cognitive impairment." Sounds good to me (read with several coats of skepticism).

With a big meal the day before, I could easily go several hours without bonking. But the bonk could happen in the middle of my work day, too, which would be bad. And I'm not sure how far I could go without bonking if I made this drastic change in eating frequency.

Suggest you read the studies rather than just accept at face value someone else's interpretation - especially a journalist.
There's an awful lot of cherry picking of studies that support a hypothesis while ignoring those studies that suggest the opposite. Really evaluate those studies about how relevant they are to you (not someone else or even a lab rat!). Are you obese? Do you have insulin resistance? Do you have negative levels of inflammation etc. etc.

Deliberately go looking for the opposing view to get a rounded view - then make your decision which might just be very reasonably to experiment and see how if works out for you. (Carry a carb gel as an insurance policy wouldn't be a bad idea.)
Maybe even consider what elite cyclists and race teams do do with all their dedicated sports nutritionists and why they do it the way they do?

Bonking to a degree is a matter of maths.
Off the top of my head I think you can store about 15g of glycogen per kg of bodyweight (check for yourself to verify - I'm no more reliable than other voices on the internet!).
After a VO2 max test in a sports science lab I know the point at which I'm burning 50/50 carbs and fat for fuel so can work out when bonking is a danger.
But that 50/50 point is a pretty low level of effort (an all day event not a 4hr event if you like) - when performance/speed is my goal I'm burning through my glycogen at a much higher rate than that. Plus the issue that performance declines and fatigue increases before you bonk.
Believe me from personal experience bonking while riding on the road isn't just inconvenient, it's very dangerous. I was so confused I cycled past a load of shops where I could have refuelled and even forgot to unclip when I stopped at a junction. That's funny, I appear to have fallen over.....

A fat adapted athlete can change those carb/fat numbers to a degree - but at what cost in performance? Again that's personal - is your goal to complete a distance or to compete or complete a distance quickly?

My longest recent ride completely unfuelled was 40 miles and I felt fine but that was fully carb loaded and at a brisk but not fast pace. If I was trying to do that 40 miles fast I would definitely have added some carbs to my drinks - maybe I would have needed them, maybe not

I have a lab tested vo2 max, but don't know when I'm burning what. Can you tell me the math for that?

If you have a lab tested VO2 max, the second thing they should have gone over with you (after they told you your VO2max) was your RER ratios at different levels of effort.

RER is respiratory exchange ratio. — it is the ratio of CO2 produced compared to O2 used. It is directly affected by the blend of carbs and fats being used for fuel.

The higher the RER, the higher the percentage of carbs used as fuel. The RER at rest is about 0.70. That is when we use the highest percentage of fat as fuel. An RER of 1.0 means that carbohydrate is the predominant fuel.

Once carbohydrate becomes the predominant substrate, it indicates an intensity at which performance is peaking, but endurance will start to decline. (I can’t remember the exact RER number —it may be 0.90–for that threshold). The intensity where that starts to shift is generally 62%-67% of VO2 max.

It is in the interests of an endurance athlete to push that threshold out as far as possible. For example, if one can remain in a relatively higher % of fat as fuel at say 70% of VO2 max, that will allow a higher level of performance at a glycogen-sparing intensity.

There are limits to how far you can do on the “fat adapted” path. At higher intensities, the body cannot produce sufficient energy via beta oxidation (that’s the process of fat metabolism) to meet the metabolic demand.

But, back to your original question. I don’t know how you were tested, but there should be a printout somewhere that shows your raw data. Usually results are printed at least minute by minute and include HR, VO2, and RER, among other things.

One of the disappointments of my career was that I never had access to metabolic testing equipment. I only underwent metabolic testing once after graduate school—that was about 8 years ago and the person screwed it up, so I never did get to actual max effort.

Do any RER studies factor in the study subjects' time and consistency in training in their life?

I'm not sure how you would quantify or categorise that, but I'm fairly sure it would make a difference if the study wasn't designed well.

sijomial · January 2020

amandaeve wrote: »

I have a lab tested vo2 max, but don't know when I'm burning what. Can you tell me the math for that?

As Azdak says you should have got a report with the results or your RER and your VO2 max number. Mine had a charts of RER against HR (plus power related data).

Cycling is the odd one out in endurance sports in that feeding/fuelling while riding is very easy, in performance terms there's really nothing to be gained by trying to extend the distance you can ride unfuelled and potentially a lot to be lost.

Personally I mostly skip breakfast (for overall calorie budgeting reasons) but consider my riding in that choice on any particular day - for moderate duration/intensity rides it's optional and an irrelevance. For long rides it becomes necessary, for high intensity medium distance rides it's beneficial.

I did a fair bit of fasted training and yes it made me better at fasted training but mostly that's an irrelevance not an actual benefit. The only real benefit to me was gaining more scheduling flexibility and hence training volume when I was doing a two day a week IF eating schedule.

Beware a lot of the myths and legends around the very few successful so called "fat adapted endurance athletes" - most of them eat a lot of carbs but timed around their exercise.

IF for active people?

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