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T2 Cycling & Lchf

GeoffersTaylor

Well-Known Member
Messages
1,084
Location
Lancashire
Type of diabetes
Type 2
Treatment type
Tablets (oral)
Dislikes
Not being able to like beer anymore!!
Hi there,
I'm recently gotten back into cycling after many many years off (recently divorced and the lady I've started seeing is a triathlete!) My fitness is coming along nicely and I'm building distance. Nothing crazy - 20-25 miles at 12-14mph is about my limit. But I did "bonk" quite hard on one ride recently so I'm wondering what I might be able to use for in-ride snacks.

I'm on a LCHF diet to help manage my T2 diabetes. I also take a small amount of metformin but nothing else. My BG levels are generally in normal range unless I get lax on carbs. I've started to carry a handful of mixed nuts on rides and some electrolytes in water. I'm very wary of energy bars and the like - I don't see much point in them if I can't metabolise the sugars.

I haven't done any BG testing pre & post-ride. Would that be worth doing and what should I look for?

And finally, whilst I'm writing, can anyone point me to where I can read about aerobic/anaerobic training?

Thanks in advance
 
I would definitely encourage pre and post (and during) ride testing.
Without knowing what your BG is, you don't know whether you "bonked" because your BG was too low (and needed extra sugar) or "bonked" because your BG was too high.

Typically, longer exercise decreases BG and interval or weight training increases BG. However, if you were cycling up hill against a string wind on a hot day, your BG may be going up due to the stress.
Generally what happens when we exercise is our liver releases extra glucose to give us the energy and our body becomes more efficient at using insulin. It is the balance of these two things which determines whether our BG goes up or down in the short term.
However, s a result of the liver release, our BG can be lower for the next 24 to 48 hours as our liver has less glucose to "drip" and is busy storing more glucose from the carbs we eat.
 
Thanks - I think I "bonked" because of being too low. That was my hunch at the time and I bought a can of coke which certainly seemed to do the trick in terms of getting me moving again (REALLY not an ideal solution - I guess my body didn't absorb that much sugar efficiently and, even worse, my hunch could have been wrong).

Because my diet is ketogenic, I'm hoping to be predominantly fat burning during rides... does that make a difference?
 
GeoffersTaylor said:
Because my diet is ketogenic, I'm hoping to be predominantly fat burning during rides... does that make a difference?
Click to expand...
To be honest, we are all different.
So, if you want to know how your cycling affects your BG, the only thing to do is to test.
Bear in mind, as you get fitter, the effects may change either because you get used to the exercise or because you start pushing yourself harder. So don't stop testing because you think you know what is going to happen. Although you probably won't have to test as often.
And, also, if you choose to follow your partner in triathlon training, the way BG changes can be different for different types of exercise.
If it was me, I would feel a spreadsheet coming on
 
helensaramay said:
If it was me, I would feel a spreadsheet coming on
Click to expand...
I'm an accountant, so I always feel a spreadsheet coming on!
My knee is ******** (technical term) so I won't be running in any triathlons, although I'm considering taking some swimming lessons because I have very poor technique and there are such things as duathlons, apparently.

Edited by Mod for language
 
Last edited by a moderator:
Cycling is doing wonders for my metabolism. Take today's readings ...
Fasting 5.1
Breakfast was pasta carbonara with wholewheat pasta (basically bacon & eggs on pasta)
2 hours later, immediately pre-ride - 6.6
50 mile ride, 4.5 hours duration. One scotch egg consumed en-route.
End of ride reading - 6.1

A 50 mile ride consumes well over 2000 calories so ...
large KFC and a pint of beer
2 hours later - 6.1.

This is typical. My body seems to consume carbs on a bike ride in a way it does not when I'm sedentary.
 
The Metformin might stop your liver compensating for the low blood glucose - it inhibits your liver, but don't consider yourself out of the running - At two years (almost) from diagnosis my knees are improving - I had to get over the aches from Metformin first, but something is definitely going on which is going counter to the normal march of time and decrepitude.
 
GeoffersTaylor said:
Because my diet is ketogenic
Click to expand...
GeoffersTaylor said:
Breakfast was pasta carbonara with wholewheat pasta
Click to expand...
The two statements above are I'm afraid incompatible..
How much pasta and are you measuring ketones?
If you are truly fat adapted then you shouldn't really be bonking as you have an enormous amount of energy stored in fat.. but if you are eating wholewheat pasta then I doubt you are in ketosis.
 
I've recently come off metformin entirely.

Of course you're right about pasta and ketosis. A lot has changed in my metabolisn these last few weeks and I'm not chasing ketosis any longer. My body is evidently willing to consume carbs on the bike when training so that's what it gets when training.

I keep carbs low when not on the bike and have moderate fats... so far it seems to be working. Stronger, leaner, faster and more stable BG all round.

It's a bit wierd, because 3 months ago I would not have countenanced pasta at all, but I'm not knocking it.
 
But if the carbs are causing the bonk then surely going back to running on fat would solve the problem. There are plenty of active people following a ketogenic way of eating to improve performance?
 
bulkbiker said:
But if the carbs are causing the bonk then surely going back to running on fat would solve the problem. There are plenty of active people following a ketogenic way of eating to improve performance?
Click to expand...

But I was running on fat at the time, there's the rub. Not a carb in sight.

What I am guessing, with the benefit of hindsight and a bit of reading, is that I pushed too hard that day and my heart rate was way up (I don't know for sure because I didn't have a heart monitor then - I do now!). As I understand it, at higher levels of intensity when you become anaerobic even-the fat adapted switch to burning the glycogen stores. There are only about 2000 calories of that and once they're gone ... bonk.

Bear in mind that I'm already significantly fitter and faster - I can now do over 50 miles at the pace I mentioned in my first post and will be doing a charity 100 mile trip next week which I have absolutely no fear of. So I don't need to push as hard to get that level of performance now.

So if I consciously keep the pace down to match a certain heartrate then I shouldn't need to consume extra carbs. It's good to see that my body will apparently use those carbs instead of getting elevated BGs so that option to fuel and then push hard seems to still be there. There seem to be a couple of training methods out there that offer this kind of approach....

I don't know - I wouldn't be asking for opinions if I did and thanks for everyone's input. I'm just going to keep experimenting, keep sharing the results and see what they tell us.

Next step, once this 100 miler is out of the way, experiment with a 30 mile route at low intensity and no carbs, then same route at a higher pace, again no carbs.
 
I'm getting confused now... so when you "bonked" you weren't eating any carbs? or you were eating some carbs but were in ketosis?
 
Back to your original issue of running out of energy when eating a ketogenic diet.

You don't tell us what you ate (and/or drank) before setting out for your ride.

I can ride around 50k on a good day (just over 30 miles) at around 12 mph fuelled by coffee with cream and butter. This gives me a reasonable amount of fat to go into my bloodstream to be burned up.

So you might have managed to stay in ketosis with your increasing exercise if you had upped the amount of fat you took on board before the ride.

I have occasionally come back low after a particularly hard (for me) ride and I agree that if you go beyond the zone where fat burning can supply all your energy your body digs into your glycogen stores as well. I think that is why endurance athletes do so well on a ketogenic diet. As long as you keep yourself "in the zone" your energy supply is almost limitless.
 
bulkbiker said:
I'm getting confused now... so when you "bonked" you weren't eating any carbs? or you were eating some carbs but were in ketosis?
Click to expand...
Sorry for the confusion. On that occasion I was in ketosis - keto strips confirmed.
 
Just consider the maths here. An elite athlete weighing just 50Kg and just 10% body fat still has 5000g of fat. At 9 calories per gramme that's 45000 calories of effort available, even for such a small lean athlete. How much more is there available for the likes of me?

I know it's not quite as simple as that but, as you say, the supply is effectively limitless if we can stay in ketosis. Where I think I went wrong on that day is that I over-exerted and depleted my glycogen stores. That's where refuelling comes in, and that's why refueling might have to be carb-based - we're not going to deplete those huge fat stores on any bike ride so there's no need to replenish them on the go. It's the glycogen used at higher intensity that needs replenishing.

This is what I'm currently thinking, anyway. I'll just keep experimenting to see if the thinking is sound and keep sharing the outcomes.
 
I think you are half right but... and its a biggie.. by constantly replenishing those glycogen stores by eating carbs you will continue to bonk and never get truly fat adapted. If you stay keto then you should have access to the energy in the fat stores 100% of the time.
 
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