Do fat stores usage always happen?

Yesterday I’ve done my first above 5 hour ride and I ate more carbs per hour than usual ( around 80gr/h ).
80gr/h felt good and I don’t think I’ll be able to add much more but despite this, my body still switched to fat stores around 4 hours into the ride.

So here’s my question :

  • Is my body switching to fat stores necessarily a sign of a lack of carbs to use for energy producing ?

I’m thinking that maybe I have enough carbs in my body, but at some point it’s not able to use them as much and has to switch to fat stores ?

It still may be a sign that 80gr/h isn’t enough though, but I’m not confident about that.

Also, do you plan your carbs intake in a linear manner ( a fixed amount per hour ), or are you flexible with it like more at the end or before big efforts ?

Not sure I’m totally following the switching to fat stores. For endurance rides a good portion of fuel is coming from fat and a smaller portion from carbs. Do you think you bonked or something or was the effort just harder after 4 hours?

Oh really ? I thought your primarly used carbs, but when you didn’t have enough left you switched to using fats.

I definitely didn’t bonk though. I went very close to bonking in the past with 50gr/h and It didn’t felt like that at all.

When I “switcht o fat stores” at the end of a long ride, I still feel fatigued but am able to go faster and ride for longer.
My legs feel better.

I’m guessing you don’t listen to the podcast often. Jonathan is always saying the body never ‘switches’ from one to the other. The body is more like a series of faders than switches. When the power is low it’s primarily fat stores. As the power rises the use of glycogen stores increases but even above threshold fat stores are still playing their part.

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Yeah, I watch parts of the podcast I’m interested in now and then.
Well I learned something new, thanks.

Now I don’t know how to explain why at the end of long rides my legs are performing better but at the same time still feel fatigued :sweat_smile:

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At rest you’re burning primarily fat. When you start working out fat and carb use will both increase progressively. At some point fat use caps out and carb use begins to predominate. The exact transition point is very individual, but as a starting point assume it happens around tempo or low sweet spot.