5K effort won't burn any fat? O_o

ChrisA

@dimitrios-kanellopoulos as far as I understand the body burns energy from different sources depending on the duration and intensity you workout:

for fast and immediate energy, muscles use energy that’s stored in the muscle itself in form of ATP which only lasts for about 10 to 20 seconds and after that the body starts converting glucose to ATP to supply the muscles with energy (faster process) and also converts fat as a supply too (slower process). So when you workout in a high HR Zone the body supplies energy first and for the bigger part from stored glucose. As far as I understand this works for 60 to 90 minutes unless your glucose supplies are used up, why runners (not me ) who can run that long should then - or better before - resupply glucose.
The conversion of fat to muscle usable energy takes longer and therefore the constant level of energy they provide is only enough for exertions in lower HR zones but this process can then go on for hours. That’s why you can walk / hike a whole day or even longer without the need to eat something.

In the end - when talking about loosing/gaining weight - it’s not so important if the body uses fat or carbs (or proteins) as an energy source but only how many calories you burn and how many you resupply by eating food as the body can convert carbs to fat and so when using a lot of carbs as energy the body can’t turn this used up carbs into bod fat anymore.

lexterm77

Beta oxidation peaks at about 60% of vo2 max and then it goes down but never to 0 because then you are dead. Same for carbs, never goes to 0 unless not alive.

https://pubmed.ncbi.nlm.nih.gov/6571234/

There is a test on how to do a beta oxidation rate
https://www.mysportscience.com/post/2015/03/18/what-is-fatmax

Out of curiosity I will do a 12h fasting 2h depletion run one time, and then repeat same run next week with carbo loading to see if burner only relies on itensity or some other trick.

ChrisA

@lexterm77 said in 5K effort won't burn any fat? O_o:

Out of curiosity I will do a 12h fasting 2h depletion run one time, and then repeat same run next week with carbo loading to see if burner only relies on itensity or some other trick.

I am think it’s intensity based only. But would be interesting to see, if fasting and a long run afterwards would show any difference compared to one, with well supplied glucose storages.

jmoneygrip

@lexterm77 it’s intensity for sure. As suggested earlier in the discussion, as you reach a higher percentage of your VO2 max your body transitions from burning fat to burning sugar (aka glycogen). This is known sport science and a big part of heart rate zone training. The burner feature is just looking at your heart rate zone.

People are different within reason but the OP already confirmed he was at or near max heart rate, we’ll all burn sugar instead of fat in that scenario so the results are not surprising.

Dimitrios Kanellopoulos

@lexterm77 once my toe is back to business, I can share with you guys how fasted long runs or intervals look like. 24-48h fasted and blood glucose levels if you are interested.

(Might have a few data from prev days as well)

Bulkan

@dimitrios-kanellopoulos yes please share. I’m interested in.

Another topic about glucose?

MiniForklift

All of my early morning runs (unless they’re going to be longer than 30km) are fasted. Supposedly we have enough glucose available to be converted to energy for at least a couple of hours of early morning activity before we start pulling it from less desirable places

Likarnik

I did a 100km ride after 18h fast and took only water with me (so in the end 21h+ fast). Almost only Z1. I expected different result:

@dimitrios-kanellopoulos said in 5K effort won't burn any fat? O_o:

@lexterm77 once my toe is back to business, I can share with you guys how fasted long runs or intervals look like. 24-48h fasted and blood glucose levels if you are interested.

(Might have a few data from prev days as well)

Totally interested. Started on fasting and also “ordered” first month of supersapiens to test.
More focus on loosing weight and stabilizing appetites etc, but everything that comes with it is bonus.

@likarnik said in 5K effort won't burn any fat? O_o:

I did a 100km ride after 18h fast and took only water with me (so in the end 21h+ fast). Almost only Z1. I expected different result:

you z1 is till 149?

Dimitrios Kanellopoulos

@andré-faria

Fasted 28h and 2+ hours workout. (does not include 30 min warmup. )

Here is the workout

Watch that witb fasted workout + not z5 the intervals (except the last that I pushed more) kept the lows of HR low (no increase as usually happens).

Blood glucose was low, expected but it didn’t have any impact.

Will test more when I am better.

Likarnik

@andré-faria yes, I calculated zones based on my LTHR (tested both on run and bike, I averaged 182bpm/20min).

@Dimitrios-Kanellopoulos great effort on 28h fast!

lexterm77

@dimitrios-kanellopoulos

This morning I was able to go 32g/h fat average that is only at 210W at 63% of VOMax. Fasted 12h and hung over.

@dimitrios-kanellopoulos Nice job, but what’s with the fasting about? If I may ask and I’m not indiscreet.

isazi

I think this [1] is not computed as HR zones, but as % of VO2max, therefore some people may see strange results if compared to the zones they have configured.

I eat pasta at least once a day, sometimes twice

[1] with this I mean the S+ app

suzzlo

@isazi said in 5K effort won't burn any fat? O_o:

I eat pasta at least once a day, sometimes twice

old way

lexterm77

I eat pasta at least once a day, sometimes twice

What good is pasta if you don’t grow/cook your own tomato sauce?

isazi

@lexterm77 never had to buy tomato sauce when I lived in Italy, my family buys few hundred kilos of tomatoes in the summer and makes sauce for the rest of the year in bottles

lexterm77

@isazi

I understand completely, I bought “tomato sauce” in a super market and I was so disappointed I started my own garden like my family did in Europe. I got maybe 5kg per plant 25plants this year, ate half of them raw if not more.

Nothing beats pasta & tomato sauce

This may be the last box this year.

Dimitrios Kanellopoulos

@andrasveres nothing is up. It’s a habit. I just eat once. Only water in-between and training.