Apparently I am a little trigger happy!
I see what you mean now. I’m sorry. I understand now that you weren’t referring to reducing dietary carb intake during workouts, and instead were referring to reduced contribution of carbs as internal fuel source. 
Agreed. I remain unconvinced that there is much we can do to independently increase fat oxidation, outside of changes in endurance fitness. Certainly unconvinced that it should be a major driver of training programming considerations.
This does seem niche - I always strayed on the side of fuelling very well rather than thinking I can bump my fat ox up by a micro %.
Could I get some advice, maybe especially from @Dr_Alex_Harrison, about nausea and electrolytes? I did a 300 km ride yesterday and totally messed up my fuelling because I had no appetite the entire ride. My usual approach is 80 g 2:1 malto:fructose + electroytes per bottle, Haribos on top of that and real food at stops. But yesterday food would just not go in so I basically just went with liquid fuel and during the last 100 km I felt very nauseous. When I got home I had a massive craving for bouillon powder and I’ve had three mugfuls of the stuff since yesterday. So that seems a pretty clear indication that I was low on electrolytes. Can that cause nausea?
Is this a joke? You ride 300km with inapropiate fueling and wonder if a lack electrolytes might have caused nausea? Why not look at the obvious fact that you underfueled and bonked?
Low electrolyte levels might play a role here, but the most likely culprit is hypoglycemia.
Ok, no need for the harsh response here. If you read my post again you will see that I struggled with lack of appetite from the start and I carried on fuelling with liquid nutrition = 60-80 g carbs/h. Yes I think I was underfuelled but only after the nausea had already set in.
You carried enough powder with you to have 60-80g carbs/h for what is most likely at least a 10h+ ride?
Yeah, I have used 50g Maltodextrin per hour for 10 hours straight without issue.
Yes I measure it out into sandwich bags
FWIW, I usually don’t consider carrying any dry powder until I’m up over 1,000g (one thousand grams, no typo) of carbs mostly dissolved in two 1-liter bottles.
Concentrate bottle 1 in front cage.
Concentrate bottle 2 in center jersey pocket.
Fresh water bottle in rear cage.
Fresh water bottle in 3rd bottle mount on seatpost.
How much electrolytes (sodium) per 80g of carbs? Or if easier, how much sodium per hour?
Nausea can be caused by a host of things in a 300km ride so kind of hard to pinpoint here!
Dehydration, hypoglycemia and any generally negative gut response to what’s being consumed or not consumed.
Absence of consumption can cause nausea and is probably my most frequent cause of nausea, personally. I usually don’t achieve that much nausea during exercise though because to be absent consumption for that long invariably has resulted in hypoglycemia and I’ve forced down enough carbs+fluid+sodium to prevent nausea before it hits.
That is an interesting system. I have a saddle bag on my seat post so that’s out, but I will think about how I could make something like that work. I like the ease of having a baseline of glucose and electrolytes always ready mixed (a bit like a drip), but its clear there are also advantages to adjusting the intake separately. I’ll also buy some extra salt chews to carry.
Found this electrolyte powder
one serving (1g) contains:
Sodium 260mg (11%RI*)
Potassium 77mg (3.7%RI*)
Calcium 47mg (5.8%RI*)
Magnesium 7.5mg (2%RI*)
One serving is not enough for 700 or 800ml bottle per hour ??
Optimal would be 750mg sodium per 700-800ml ??
If I do my workouts in the morming, with usually just a banana before and a bottle of carbs during, should I focus on simple or complex carbs for my post-ride-meal?
never tried to consume 100g of carbs/hour so kinda new to this osmolality thing or what ever it is. So how much do i need to care about it? Let say i put 100 grams of white sugar on 500ml bottle and drink it during one hour. Whats going to happen? Gut issues? Should i drink more water than that because im getting that amount of carbs…?
probably depends how hard you go.
i usually eat two bananas and then go for sugar water on top. Personally, I just eat a bowl of porridge with a load of fruit afterwards
Depends on how much you’re sweating. For a short, hard, cool, low-sweat ride, you might get away with 20% concentration. 100g carbs per 500mL = 20%. 100g per 1 L = 10%. FYI.
Osmolarity = number of molecules per liter of solution, and matters much less. But makes a great marketing word for a lot of companies peddling high-maltodextrin beverages! “isoosmolar!” “gut neutral” “low osmolarity” etc.
For gut tolerance, what matters more is grams of carbs per hour, current hydration status, and concentration of beverage.
Yes, in general drinking more water with 100g carbs is probably a good call. Play with it. Let us know what you find out works for you. I’m currently exploring what the upper ends of concentration limit tolerance is, for low-sweat rate activities. so if you find out you can do 100g carbs per 500mL (20% concentration) for 2-4 hrs with no GI issues, I’d love to hear about it.
Haven’t you previouly recommended that people build up to higher g/hour consumption gradually? As in add an extra 10g per bottle or so over a few rides? That’s certainly the (successful) approach I took after reading the massive threads on here and slowtwitch and I’m pretty sure I was following advice from yourself or others…
Also, do you have any insight into how gut tolerance of 90/100 g/hour is maintained? I hit a training peak for an A-race a couple of weeks ago, so now I’m easing off for training and consuming less g/hour for shorter/easier rides. I guess that I should gradually ramp up carbs as I ramp up training duration/intensity in the next blocks… I suppose I could not bother, and jump back to 100g/hour when needed, but I’d like to avoid any unpleasantness !
Thanks
Most folks can handle jumping up to 70-80g/hr with zero gut training. It just requires good implementation (sufficient water + sodium intake).
I wouldn’t bother with a ramp-up.
There are lots of folks who can make the jump to 100g/hr with no gut training whatsoever. Total gut adaptation is probably on the magnitude of 10-20g/hr, if I had to guess. So if you know you’ve been capable of 100g/hr in the past, (I’d bet you’ve been capable of 110g/hr and just not pushed it), then you’re probably still very much capable of tolerating 90g/hr. Possibly still 100g/hr or more.
I’ll posit that gut training is as much as about user implementation training as it is anything else. Sure there are some real cellular gut adaptations but I don’t think they account for most of the GI issue prevention that comes with typical gut training ‘protocol’ that are being pushed left and right these days.
If you have one bottle of 20% solution, and one bottle of just water, and drink from them rougly evenly, do you count it as 10% solution?
Brilliant info, thank you