Kilojoules in vs kilojoules burned

[Curlyboy 1]

I have a question. For my tri training I burn in excess of 15,000 kJ everyday. 

A medium Big Mac meal is 4,200 kilojoules. 

Hypothetically, could I eat just 3 Big Mac meals a day and lose weight ??

 

[dazmuzza 141]

I think if you're burning 3,500 calories (or 15,000 kjs) a day in tri training, you're going to probably injure yourself soon enough. That's a lot of energy burned per day I would suspect. 

By maths, yeah you might - but I just don't think its practical to do that amount of training and survive on Big Mac meals 🙂

Edited July 8 by dazmuzza

[Peter 3,468]

Agree Daz.  Thats 6 hours exercise a day.  Fine for a one off day but back to back, would be impressive.

[Stikman 1,778]

Perhaps that's including non-exercise burn, like Garmin reports it?  If so then I can get that with less than an hour of running and I work in a relatively inactive job.  Us bigger blokes can go through a lot of Big Macs just breathing.

Yes, you could do it but I'd suggest it's probably not a great way to go about it.  I'd exchange one of the meals for nuggets instead.

[Alex Simmons 725]

25 minutes ago, Curlyboy said:

For my tri training I burn in excess of 15,000 kJ everyday.

What brand of random number generator are you using to *cough* measure that?

[IronmanFoz 1,336]

52 minutes ago, Curlyboy said:

I have a question. For my tri training I burn in excess of 15,000 kJ everyday. 

A medium Big Mac meal is 4,200 kilojoules. 

Hypothetically, could I eat just 3 Big Mac meals a day and lose weight ??

 

In theory yes. Input v’s output. 

Would love to know how you achieve these numbers.

But in relation to the Big Mac. My thoughts would be - you can eat a lot better. You need a balanced diet.

However..... I still reckon a good diet and then every now and again after a big training weekend - a good Mac attack meal is good on a Monday...... plenty of fibre, protein, fats, salt and a few greens (pickle and lettuce) - would also be good psychologically because you deserved it.

[Flanman 2,277]

https://www.healthline.com/nutrition/debunking-the-calorie-myth

FM

[Curlyboy 1]

Yes,  this is including whole day ( non exercise)

[Curlyboy 1]

Thanks for the feedback. I don’t plan on eating them every day. But I do enjoy them every now and then. My training partner said I could not eat them without putting on weight. I said based on the maths that’s incorrect. 

[dazmuzza 141]

Just now, Curlyboy said:

Thanks for the feedback. I don’t plan on eating them every day. But I do enjoy them every now and then. My training partner said I could not eat them without putting on weight. I said based on the maths that’s incorrect. 

Well you just asked the math question - there are heaps of other variables (I'd also look at flanman's link posted above about the impact of hormones, insulin etc. ).

If you're serious about training and being fast and all that, it's just best to avoid junk food as much as possible. By no means ban it altogether, but just avoid eating it regularly and you should be fine. 

[Curlyboy 1]

Thanks. I like to fast but for me it’s more about the participation. 👍🏻

[Bored@work 3,674]

On Saturday I rode 132km & burnt 3515 calories. Or as I like to say I can eat 7 donuts guilt free.

 

 

[Peter 3,468]

14 minutes ago, Bored@work said:

On Saturday I rode 132km & burnt 3515 calories. Or as I like to say I can eat 7 donuts guilt free.

 

 

Donuts are scared of you. 

 

[Pete 468]

23 hours ago, Flanman said:

https://www.healthline.com/nutrition/debunking-the-calorie-myth

FM

a quote from the above link:

"If we take in more energy (calories) than we expend, we gain weight. If we expend more energy than we take in, we lose weight. This is an unbreakable law of physics and isn't even debatable." 

..which kind of kills their whole premise! Thus the only thing you can debate is the efficiency, or how much more energy we expend overall for a given effort. Typically, leg-based exercise is around 25% efficient - so if we take the average watts (joules/second) and multiply this by the time we get the total energy in joules - and there's just over 4 joules per calorie.

Another "fun" energy fact - you can calculate the energy required for vertical ascent by the simple formula energy (in joules) = m.g.h. where m is the mass in kgs, g = 9.81 m/s**2 and h is the height in meters. This formula is kinda cool for working out how many watts you need to expend to do a climb in a certain time and how the effort is directly proportional to weight...  something I know only too well

[Alex Simmons 725]

5 hours ago, Pete said:

Another "fun" energy fact - you can calculate the energy required for vertical ascent by the simple formula energy (in joules) = m.g.h. where m is the mass in kgs, g = 9.81 m/s**2 and h is the height in meters. This formula is kinda cool for working out how many watts you need to expend to do a climb in a certain time and how the effort is directly proportional to weight...

At steep gradients this accounts for around 90% of the energy demand. At shallower gradients though the less linear this relationship becomes and energy demand is more shared amongst factors other than an increase in gravitational potential (e.g. overcoming air and rolling resistance).

Another fun fact:
Coefficient of rolling resistance is effectively equivalent to gradient. e.g. a Crr of 0.005 (0.005=0.5%)* is the same in energy terms as adding to the 0.5% gradient. IOW choosing low rolling resistance tyres (or using the right tyre pressure) is akin to choosing to ride up a less steep hill.

*  About the Crr of good tyres on a typical asphalt road

[Pete 468]

18 hours ago, Alex Simmons said:

At steep gradients this accounts for around 90% of the energy demand. At shallower gradients though the less linear this relationship becomes and energy demand is more shared amongst factors other than an increase in gravitational potential (e.g. overcoming air and rolling resistance).

Another fun fact:
Coefficient of rolling resistance is effectively equivalent to gradient. e.g. a Crr of 0.005 (0.005=0.5%)* is the same in energy terms as adding to the 0.5% gradient. IOW choosing low rolling resistance tyres (or using the right tyre pressure) is akin to choosing to ride up a less steep hill.

*  About the Crr of good tyres on a typical asphalt road

Sorry for the thread hijack folks but I just gots to know....!

You know Alex, that is the most interesting thing I've heard in ages.  Is there a low RR alternative to the classic Conti GPS 4000s tyre with bog standard garden variety tubes?  Are latex tubes still a thing? Also, my understanding is that super high pressure (say 120?) always means lower RR than lower pressure (say, 90?). Love to hear your thoughts on this!

[dazaau 323]

On 08/07/2019 at 4:29 PM, Curlyboy said:

Thanks for the feedback. I don’t plan on eating them every day. But I do enjoy them every now and then. My training partner said I could not eat them without putting on weight. I said based on the maths that’s incorrect. 

Pfft, of course you can lose weight while eating some junk food. And I would know. 

[Alex Simmons 725]

2 hours ago, Pete said:

Is there a low RR alternative to the classic Conti GPS 4000s tyre with bog standard garden variety tubes?

Probably (e.g. the GP 5000), but I don't do Crr research. There are a few places that do, e.g.:
https://www.bicyclerollingresistance.com/

but this is by no means the only source.

 

2 hours ago, Pete said:

Are latex tubes still a thing?

 

Yes and they will always provide a lower Crr than a butyl equivalent. If speed matters, then use a good latex tube.

 

2 hours ago, Pete said:

Also, my understanding is that super high pressure (say 120?) always means lower RR than lower pressure (say, 90?).

Higher pressures are only desirable on near perfect surfaces, e.g. an excellent wooden velodrome. In just about every outdoor environment we experience in Australia I would expect 90psi will more likely yield a lower Crr than 120psi. Most people over inflate their tyres.

[rory-dognz 649]

2 minutes ago, Alex Simmons said:

Yes and they will always provide a lower Crr than a butyl equivalent. If speed matters, then use a good latex tube.

 

Higher pressures are only desirable on near perfect surfaces, e.g. an excellent wooden velodrome. In just about every outdoor environment we experience in Australia I would expect 90psi will more likely yield a lower Crr than 120psi. Most people over inflate their tyres.

Would a tubeless have a lower ver than a tire and latex tube?. Eg gp5000 comes in both tube and tubeless options 

[pieman 1,295]

33 minutes ago, rory-dognz said:

Would a tubeless have a lower ver than a tire and latex tube?. Eg gp5000 comes in both tube and tubeless options 

I think all the tubeless tires test faster in that setup as opposed to with latex tubes