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Sunday, February 3, 2019

Fat as Fuel for Endurance Activities

I have been dabbling in the "low carb" world in recent months.

It all started with Intermittent Fasting and the Jason Fung theory that insulin resistance is the key factor that leads to obesity.

I'm not 100% convinced that he is correct - but at the same time I have been losing weight with Intermittent Fasting and reducing carbohydrate (especially refined and sugar).

Next question was - can you perform athletically without carbs?

This is where life gets difficult.

Evangelists like Timothy Noakes emphatically say "yes".  There are athletes like Zack Bitter who are running Ultramarathons on High-Fat-Low-Carb diets.

Finally I found a very good summary in this article.

Adapting to Fat over Carbs

This was interesting to me, because it implies you can train your body to prefer fat longer.
Maximal fat oxidation has been reported to occur between 47 and 75% of VO2max, and varies between trained and untrained men and women [1, 5, 6]. Nonetheless, MFO has been observed to range from 0.17–1.27 g/min [7], where ketogenic adapted individuals can exceed ≥1.5 g/min
This is from the article, it shows the concept:


So that MFO point is not static - you can move the point to the right (ie. to higher intensities) with fat adaption.

... But There Is a Limit

Back to the article:
However, during sustained high intensity exercise (>70% VO2max) which is common during competition, CHO is the primary substrate relied upon despite short and long term fat acclimation
In other words - fat adapt all you want, if intensity gets too high, you're going to need carbs (CHO).

The Bottom Line

It seems entirely possible to perform at medium intensity on fat - but once the intensity ratchets up, you need carbs.

How I'm Applying This

Day to day, I'm using Intermittent Fasting, avoiding processed carbohydrate, and generally eating a higher fat lower carbohydrate diet.  It has resulted in weight loss and I generally have felt better.

In training, though - I tinkered with fasted runs and with not supplementing with carbs.

It works OK, but since re-introducing sugar to my high intensity workouts I've felt a whole lot better.  It is like rocket fuel!  When I race I will certain use carbs to enhance performance.

Is that the end of fasted runs/rides?  Certainly not!  I will continue to use the no-carb run/ride when intensity is low, to teach my body to use fat more efficiently and not rely on "rocket fuel".  I have some very long endurance events planned this year, the only way they will go well is to become a lean, mean, fat-burning machine!

All things in moderation.

Saturday, January 19, 2019

Weight Loss at 4 Months

Stoopid Christmas.

... so basically I'm where I was early December.

Pre-Christmas office parties and get togethers, followed by Christmas week and change of being way off plan.

Didn't do much fasting, and certainly wan't low carb.

Back at it post-Christmas.  Tried to do it abruptly but that failed.  Now back to the gradual process that was working.

Intermittent Fasting

16-24h fasts daily.  Fit around life events.

Low Carb

I was trying very low carb with a goal of ketosis - but this wasn't working well for me.

Instead I'm doing very low processed carbs.  It's been better for my overall energy levels, my mental health, and it's made my runs/bikes more effective.

I have to write a blog post about this wonderful study that I found.  Long story short, though - for endurance activity, you need carbs to do higher intensity workouts... and there's good reason to do some fasted workouts as well.

Low Alcohol

After the holidays I had to re-re-adjust my alcohol intake back to guideline levels.  This hasn't been tough, just stopped buying the IPAs I've grown to love, as they have higher alcohol levels... back to 4-5% beer.  I don't feel compelled to drink any more 4-5% beer than I do 6-8% beer!

There are a lot of good Session Ales, some of them pretty hoppy and flavourful, and mostly around 4-5%.


I mention exercise last as it feels like it has the least impact on weight.


I've managed to start pushing some pace, though.  I'm still heavy (204lbs-ish) so I'm not lightning fast, but building the speed at this weight should pay dividends once I manage to drop it!


... just running, biking, doing the odd row / core workout... eating right... losing weight

Monday, December 31, 2018


I was sick a lot (hopefully something I've figured out, lousy sinusitis!).  
I missed the Chicago Marathon as a result.
Hours down.
Kilometers down.

Worst of all ... weight was a struggle ... until I really found out why and reversed the damage.
June was the only real bright spot.

We did the new course of Storm the Trent - that was awesome.  

And then the 24 Hour MTB race tag-team - first time, it was fun, great learning experience!  We'll be back for 2019.  Discovered riding at night in the woods in the process, which is a real thrill.


I have one goal.  I will lose weight.  And I finally figured out how.  

I know not everyone is with me on this ride - but I'm now using a low-carb and intermittent fasting approach.  The fasting especially has been remarkable.  From September to Christmas I was down about 10 lbs overall - I've gained back a couple over the holidays, but as the clock strikes midnight I'm ready to rock.

This weight is going bye-bye.


Storm The Trent - going back, this time to do the Trek distance.  Canoe, mountain bike, run, navigate - it's a wicked awesome fun adventure.

24 Hours of Summer Solstice - going back, tag-team again!  New bike should ease the bumpiness, give me more comfort over the ~12h of riding I'll be doing, and more confidence.

Muskoka River X - stepping up to the full distance, 130km!  It's a canoe race.  We've done the shorter 80km before, but this is a 20h+ adventure, and includes up-stream paddling.  Lots of portages.  It's going to be painful and awful - and AWESOME.  Obviously.

Chicago Marathon - signed up again after missing last year.  This year I'll be there.  And I'll be light.

Really looking forward to the adventure!  I know there will be highs and lows, but I have a good feeling.

Wednesday, December 12, 2018

Weight Loss at 3 Months

The plan was really just to try Intermittent Fasting, but to be more aggressive with the fasting.

The Obesity Code

I based my strategy on "The Obesity Code" by Jason Fung.

He theorizes that we are fat because of insulin resistance, and that the best way to fight it is to spend more time in a low insulin state.  He recommends intermittent fasting as the primary tool.

Everything in his book spoke to me - the way I was hungry all the time (ALL the time), the way that I would do 10h/week of exercise and still gain weight, the way that calorie counting worked for short term but my weight would always, always come back...

Without further ado - here are my results so far.

The blue dots are the daily measurements - they fluctuate a lot, based on when I was fasting/exercising/etc.

In 3 months I've lost about 10 pounds.

For people who have followed my blog and life, you'll know I've tried to lose weight over and over.

I had success with counting calories, for years.
I added in exercise - copious amounts.  Ironman!
When my weight would go up - I'd count calories again.

But it became harder and harder.

If you believe Fung, it could be that my insulin resistance simply got worse and worse.  I believe this, partially because I had a blood test where my doctor told me so!  I was on a bad road, and I feel like carbs played the lead role.

The first 6 weeks...

Some of the fasting time isn't actually on that chart - the weight just didn't come off immediately.  It took about 6 weeks for anything to happen, which felt like an eternity.

Then one day... the weight started coming off.

Actually before that... I remember one day saying to my wife "I don't feel hungry!".

It was a revelation.  I was sitting on the couch, watching TV, and I wasn't hungry for food.

I was always hungry before that.

It's a weird thing with fasting - you think you'll be hungrier, but the opposite happens.  I'm never hungry in the morning.  I'm rarely hungry throughout the day.  I get a little peckish in the evening, but much less than the ferocious hunger I used to feel.

When am I most hungry?  After I eat carbs, especially sugar.  It's like crack cocaine, I become obsessed with getting more.  (I assume that's what crack is like, right?)


I started checking my ketones early on, and they kept coming back negative.  Then I took the "low carb" diet more seriously... eventually I figured it out.  I can get into ketosis at will now.

The easiest way is to run or bike while fasted, or having eaten very few carbs.  In the immediate aftermath there won't be ketones (your body sucks them up as fuel!) - but a few hours later?  Dark purple on the strip.

Even days when I feel like I really pigged out, if it was on high fat / low carb food?  The scale gives me a good number the next day.  It's pretty amazing.


Jason Fung's magic to me is that he doesn't prescribe some exact regiment.

"Thou shalt fast exactly 20 hours a day and feast exactly 4"
"Thou shalt never eat cake"
... etc.

You can't sustain that.  He says as much - Atkins fails because most people will eventually cheat, and it snowballs.

Build the approach around your lifestyle.  Your daughter has a birthday party?  Go!  Eat cake.  Pizza.  Have fun.  Don't give it a second thought.  Fast the rest of the day, before you go to the party.  Or fast after!

It's not a religion - you just always have to understand the insulin has to be low most of the time, and arrange eating/fasting windows around that.

He does tend to advise longer fasts - 24h or 36h - rather than 16:8.  This worked better for me.  Now I'm pretty regularly doing about 20h fast, 4h feed - but like I said, I'm not religious about it.  I fit it to what I'm doing that day.


I'm excited.  This has been a great little run, and I'm looking really forward to keeping it going into 2019!  I feel like I finally found something that really really works, and addresses the root issue.

Sunday, November 25, 2018

My Long Slow Fat Adaption

When you listen to guys like Dr. Timothy Noakes, they talk about the notion of being "fat adapted".

The idea is if you restrict carbs, your body starts to use fat as its primary fuel.  This is backed up in studies - at the end of carb-restricted training periods, the fad adapted athletes burn 2.5 times as much fat for fuel, and they do this from the very start of their activity.

Here are my experiment runs...

Run 1.  20km, 6:30/km.  Bonked bad.  3 weeks into IF.

Run 2.  21.1km  6:09/km.  Better.  Almost 2 months of IF, 2 weeks of HFLC (sporadic).

Run 3.  21.1km  5:52/km.  Much better.  Almost 3 months of IF, using HFLC more regularly.  Felt strong and comfortable.

The really interesting thing about Run 3 is that I was actually 16h fasted and consumed zero calories during the run.  I had nothing but black coffee and water for 16 hours, plus another 2 hours of running.

In fact, I had biked the day before for 1.5h (water only), and had eaten HFLC the rest of the day.  So I hadn't had any kind of significant carb for almost 2 days, and had even burnt off some of what I would have had stored on that bike ride.

I find this all remarkable. It's exactly what Noakes predicts, but it still goes against so much orthodoxy.  I was kind of sure it would fail.  I'm shocked.

Questions still remain

Am I able to perform better than I did as a high carb athlete?  Sure I can get through a 21.1km long slow run, but can I push the pace?

Can I actually go longer?  How much longer?

Is the weight loss permanent?  (I'm down about 10lbs so far, give or take).  Or like most calorie restricted diets, will it come back, and bring friends?

I also still have some questions about "high fat, low carb" vs fasting - the athletes seem to be doing HFLC and I can't find much about fasted athletes.  I'm guessing it's because they're generally not overweight to start with, so fasting doesn't really enter the equation.  My main question: does it matter during activities if the fat I'm burning is coming from my (ample) stores rather than from food I just ate??  I'm still trying to find the answer to that.

From Experiment to Lifestyle Change

I'm making this permanent.  Even if my performance were to suffer (and I'm not sure yet if that's the case, but if) I am meeting my real goals.  I'm losing weight.  I feel great.  My mood is great, even.  I'm able to do the activities I love. 

To the moon, Alice!

Sunday, November 18, 2018

Performing Fasted: The Debate Around Fat and Performance

There's a wild debate in the fitness community between the High-Fat-Low-Carb (HFLC/Ketogenic) folks and the traditional High-Carb-Low-Fat folks.

(Protein just kicks around in the middle - let's park him for now)

Tradition says: eat carbs, a lot of them, they're your most effective source of fuel.

HFLC says: you can do just as well (better?) using fat as a primary fuel.

Who is right?

It's really difficult to discern.  

Dr Timothy Noakes

Most recently I listened to the Velonews Podcast "Inside Ketogenic and High Fat Diets".
Click here to listen.

They interviewed Dr. Timothy Noakes - who wrote "The Lore of Running" which praised carbs... only to in recent years do a 180 degree turn and support a HFLC/Keto regimen.  It is a fascinating listen.

Fat: More Energy, More Stored

One undisputable fact is that you have tens of thousands of calories of fat available to you on your body, vs only a couple thousand tops of carbohydrates.  So fat has to play some role when you get into longer endurance sports.

Studies have shown that fat-adapted athletes (those who have been on low carbs for 6-8 weeks, generally) can metabolize 2.5 times more fat per hour.  I did some quick math and it comes out to 600kCal based on some studies.  That's a very big chunk of what I need, just from the fat I already have too much for.

Performance ... Wither Efficiency?

This is where the crux of the debate is.  The good thing about carbs - they are stored in your muscles and are ready to go.  Even when you ingest glucose - it goes straight to the blood stream, it's metabolized easily and quickly.

So can fat, which has a longer metabolic pathway from need to burn, compete?

Some studies have suggested "No".  This article does a pretty good job looking at one of the studies - during a training camp, athletes who switched to a HFLC diet failed to gain any performance, vs the regular carb athletes.

Hold on, says Dr Noakes.  Those athletes weren't already fat adapted, so they were going through the adaptation while taking on hard training - maybe the results would have been different if they were already fat adapted!

It's hard to tease out for sure.  If I were an Olympian with lofty performance goals I would stick to tradition until the science is clearer.  Noakes works with those folks, though, so maybe not!

Jono's Efficiency

I have been doing intermittent fasting for about 11 weeks now, which isn't exactly the same as HFLC but at the same time it kind of is.  Low carbs, relying on fat.  When I do eat I have been lowering carbs, although not religiously.

What have I noticed during fasted runs/rides?  

Higher heart rate for sure - about 10bpm higher for equivalent running pace, poking up into the 180bpm range often with 175bpm average.  For me that's crazy territory, 180bpm is close to "sprinting to the finish".

Noakes dismisses this - sure you need more oxygen to burn fat, so what?  

My results somewhat back this up - my heart rate was high enough that I should have been completely wiped after 5km, but I did 12km with hills... so could be that my heart needs to beat faster, but am I necessarily less efficient?  Will I run out of energy and be done?

I'm going to keep chugging and monitoring it.  My goals aren't the same as an Olympian, I want to lose weight (and I'm down a whoooole bunch!) and be healthy, performance is really secondary, so I can afford to take a risk on performance.

Friday, October 12, 2018

The 36h Fast

36 hours has been my longest fast to date.

I'm not sure I will push it further - I might.  It went fantastically well.

I Gots Energy!

I feel fantastic.  I have energy, I'm not tired.  I'm not hungry. My mood is great.

Sure there were a few dips during the 36h, and the odd hunger pang - but I have dips every day, and odd hunger pangs. 

In fact I would say my hunger was less than between meals on a regular eating day!  And way less than when I try to reduce calories. I think that's what makes fasting so appealing (and, frankly, bizarre).

I did something to make it a bit crazier - I ran 15km at the 22h mark of the fast, on just water.  Well, technically, lemon juice and water with a bit of salt... to each one's own!  No calories, though, which is the main point.

I was slower than I'd have been fully carb'd up carrying a bottle of Gatorade - no question. But I did it, and didn't feel bad.  I've done a few fasted runs leading up to this, so I figure it's my body adapting.  In studies fat-adapted athletes were able to metabolize 2.5 times as much fat as high carb athletes.

Fat For Fuel

Fat is not as efficient of a fuel - true. 

Fat is not already in your muscle like muscle glycogen is - true.

But there's a whoooolllle lot of it.  If one turns to ultra-endurance then fat is going to be a big part of how you get to the end.  Better learn to burn it for fuel!


I'm down about 8 pounds since September (some I'm sure is water/etc!) as of this morning, 36h fasted.  Even unfasted I'm down ~4 pounds, so some of it is definitely real weight loss.

Going to keep on it!  Feels like I finally hit on something that works.