Training the gut

So basically i’ve been trying to up my intake within workouts but not feeling good or any benefits. I have tested two fueling options below with the results as shown very similar calories and carbs over the meal + workout food. Rides / workouts are generally around 1.5-2 hours currently so not huge with around 1k KJ - 1.3k KJ output.

Option 1
Breakfast - 650 kcal Ride fuel - 360kcal (60g c / h)
Feeling - Very bonking not great, feels like blood sugar is all over the place.

Options 2
Breakfast - 1000kcal ish Ride fuel - 80kcal (20g c)
Feeling - Stable energy great power.

My question is, is this a case of training the gut more? As currently it’s clearly not digesting or using the fuel well when i have a higher input during. Or just not worry as the rides aren’t hugely long anyway? As long as daily energy intake covers output.

What are you having for breakfast and what is the timing relative to the workout?


Typically a smoothie / oats / rice and some eggs or fish. When fueling on the bike option there would be less carbs and overall kcals. So scaled down. Time wise usually 1.5-2 hour pre.

Complicated answer is there’s a whole bunch of stuff to look at including what you ate the night before, what you had for breakfast (slow release vs quick release), how long you ate breakfast before riding, and how intense the workouts are!

Simple answer is if option 2 is working great for you, do that. If your rides and events aren’t too long then ability to maximise carb absorption isn’t a limiting factor so not something you particularly need to worry about.

Personally I’d struggle to digest things like eggs or fish with only a 1.5-2 hour window before a hard ride. Fine for Z2 stuff, maybe tempo and sweetspot. But if it was more like threshold or VO2 work I’d either need to eat earlier or just stick to stuff like oats, toast, fruit. For me, unless it’s a race where I’ll make the effort to get up early and have a good breakfast at least 2 hours before it starts, I’m more typically having a light breakfast, getting on the bike within 30 minutes, and then fuelling on the bike as necessary. Big meal the night before is a huge help as means glycogen stores are already pretty full and I’m just topping up. Nutrition during the ride might mean proper sports nutrition with a glucose/fructose mix to maximise absorption if it’s a key ride or race. Or if it’s lower intensity and there’s a bit more flexibility in what I eat then I prefer to stick to more solid food like bananas, homemade oatmeal bars, that kind of thing.


If you’re eating lots of carbs 1.5 to 2 hours before the ride, and only riding 1.5 to 2 hours, you’re pretty loaded up already.

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A smoothie is ok for fast burning carbs i guess. Oats are excellent breakfast food as they are fairly slow burning carbs.
Eggs and Fish will contribute nothing at all to your workout. They are good sources of protein and fats but these are not what is needed for a workout.

For fuelling on the bike think about what science and marketing have come up with as the optimal solution: little sachets of sticky gels with 20g carbs based on fructose & glucose. You can replicate this with basically any other sugary thing. For a race you might be looking at trying to get 4 or 5 gels in per hour so that’s the sort of burn rate you might need. If you’re only going for 1 or 2 hours you’ve probably alreaday got most of what you need in your energy stores. Maybe just top up with a couple of gels.

Interesting i guess everyone is different. I have found if i only eat carbs at breakfast i’ll bonk out the door. Seem to get reactive hypoglycemia a bit.

As an example for yesterday. This is what i had pre V02 Max 4 min intervals.

Smoothie - 1 banana, 1/2 cup oats, greek yog, whey, berries
Eggs - many (these are eaten first and stabilise blood sugar for me)

No stomach discomfort at all and energy wise was good. Screen shot from interval data below. Just find it weird that that works and when adding sugar on the bike either in bottle or in simple forms (soreen) i feel bad. Kinda like blood sugar is spiking and dropping. What i haven’t tried yet is doing both, big breakfast and then fuelling on the bike but can’t see i really need it.

That 45m-2ish hr window might be the worst for having breakfast before a ride because (as you said) that is when your blood sugar tends to be the lowest. Though that smoothie you had is pretty heavy in fat and protein so it shouldn’t cause a massive blood sugar spike in the first place. I wonder if just by having a 50% larger breakfast you are stretching that digestion window so when you get on the bike you are still getting a trickle of carbs from the breakfast. While with option 1 you’ve completed the digestion more and had your blood sugar fall.

For Options 1 and 2 how are you subtracting 350kcal from the breakfast? If you are cutting that smoothie in half then I could maybe see how you feel low energy during your workout. Especially if you dinner the night before it typically lower carb.

Yeah i kinda just scaled things down. Probs more be like rice and eggs when fuelling on the bike option.

I used to have big carby dinners but recently found if i have a lower carb (40g) and less kcals i sleep so much deeper which makes the next day way way better. Probs as a big dinner with lots of carbs causing blood sugar spikes and dips and takes longer to digest.

Yeah, if you are doing lower carb dinners then the carbs at breakfast become more important. We can’t say for sure why opt 1 works worse than opt 2 but in the end what works for you works for you. The only issue might be if you have a long ride and find you can only take in 20g/hr for some reason. Then you’ll definitely need to find a way to eat more on your ride.

I find with early morning workouts, skip breakfast altogether and going with up to 90g/hr mix works for me. I have just got a 3 pack of supersapiens CGM to dial this in, First ride with one on today and I had a bowl of granola + greek yoghurt 1:30 before my lunch threshold ride (as I normally eat a mid morning snack, but usually I work out before breakfast) and my blood glucose was tanked just before the ride, during I felt like crap. I couldn’t get it up either, even with 30g carbs in a bottle and 3x20g gels…

Look forward to testing a ‘fasted’ ride with lots of liquid carbs during as this is what seems to work for me, be interesting to see if the feeling marries up with blood glucose reading

Yeah this is where im worried. Can smash out 2h threshold rides easy but after this it does become hard. Hense why i think the issue might be training the gut…

Your “gut” is insanely individual. What works and doesn’t work is really going to be you to figure out.

I can do an XC race (1.5-2 hours) fastest with only water in my bottles and have the same performance as fueling up. I don’t know how much of that is from my odd gut, and how much of that was from years of being fasted for hours every day from virtually never eating breakfast in my life.

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