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Daily energy expenditure through the human life course

research.brighton.ac.uk

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Re: Daily energy expenditure through the human life course

#221

Post by layla5alive »

naijaboiler wrote: post #216
Jenda_ wrote: post #203

Earlier quoted context omitted.

I don't understand where does the excess basal energy expenditure go. Do persons like the OP when <25 y.o. produce significantly more heat (e.g. wearing only t-shirt and shorts even in winter, and "dying" in the summer)? Does the skinnier body mean way bigger heat losses, even when compared to bigger surface area after getting fat (i.e., way higher surface temperature)? (presumably yes, but to this extent?) The artic…

one possible explanation for me, calories ingested != caloric intake. I ate more, pooped more. So even if my body's metabolic efficiency didn't change, perhaps my ability to extract calories from what i ate changed. Sitting down and eating 6 plates of pasta at Fazolis all-you-can-eat for $4 (or $6) + 12 breadsticks every wednesday evening, is not something you can misremember. i was a broke student, and it was most e…

I believe you, naijaboiler.

Posts like Jenda's are depressingly unimaginative.

I wish HNers, and people in general, would learn some biology, and use some critical thinking to imagine that when something doesn't fit their very basic mental model, that's probably because there's exponentially more to know/learn(!). Maybe then they would stop thoughtlessly regurgitating such basic misconceptions.

Biology has so much complexity, but so many people want to insist calories in MUST balance calories out, without any exceptions. As if humans are just burning our foods at 100% efficiency in a bomb calorimiter. Biology isn't this boring.

Forgetting digestion and a host of other variably efficient processes, Mitochondria produce ATP from various possible substrates. These substrates are not equally efficient at producing ATP. So just here, in the simplest form, you have a mechanism by which input energy can be wasted or conserved.

Separately, when demand for ATP has suddenly ceased, Mitochondria can change modes to deterministically waste huge amounts of energy to avoid over-producing ROS. So even in the same cell, even provided the same substrates, efficiently can be dialed up and down rapidly.

And we haven't dug deeply into anything. There are so incredibly many processes with highly variable efficiency.

There's much more that we have yet to learn than that we know. Don't underestimate the complexity of biology.

Re: Daily energy expenditure through the human life course

#222

Post by eastbound »

ashconnor wrote: post #217
naijaboiler wrote: post #147

Earlier quoted context omitted.

No I legit ate way much much more in my 20s. I'm not misremembering. I ate more

I was rake thin until I started lifting weights with a buddy of mine at university. However it wasn't until I started GOMAD that I noticed any muscle and weight gain. Before that I was eating crap. Lots of things that I that were high in calories but not enough of them throughout the day to exceed my metabolism or get close to the amount of protein I needed. I think if you could go back in time and count the calories…

Maybe lifting weights => Body actually uses and stores all food => Fat at 40?

Whereas a thin man who doesn’t do sports never gets really fat?

Re: Daily energy expenditure through the human life course

#223

Post by blipvert »

nradov wrote: post #142
blipvert wrote: post #95

Earlier quoted context omitted.

That is an insane amount of training - big lifestyle changes! I increased my calorific needs by 1000 a day by doing a 10K run (1hr) before breakfast. Still a 160lb weakling :)

That seems high. Someone your weight would generally only burn about 750 kcal on that workout.

It’s what Strava says I’m burning so I can only go by that. 750 would still be above the low end of the range quoted by the OP.

The amount of extra food I needed to start eating!

Re: Daily energy expenditure through the human life course

#224

Post by tonyedgecombe »

paulpauper wrote: post #188
missedthecue wrote: post #126

Earlier quoted context omitted.

That's also completely canceled out by enjoying a single 32oz soda. Walking a lot and having a bad diet rarely even each other out. And it's so easy to cancel it out I don't think most people realize. A brisk 2km walk burns less calories than are consumed when eating two regular Oreos.

It is even worse than that. The conversion rate of activity to net calorie loss is not 1 to 1 . It can be zero or even negative, at least based on my own experience and other people. You see people on Reddit subs do 10k steps and tons of walking, hardly lose any weight. It's all about not overeating.

One of the problems is people naturally adjust their activity levels after exercise. After a two hour bike ride they will spend the evening on the sofa. It seems we naturally adjust without consciously thinking about it.

Re: Daily energy expenditure through the human life course

#225

Post by [deleted] »

hiAndrewQuinn wrote: post #37
logicchains wrote: post #34

Muscle burns more energy than fat. As people age, their muscle mass declines without sufficient exercise, so we'd naturally expect the average person's metabolism to decline via this even if "metabolism per kg muscle" didn't change.

This is exactly the kind of clear headed reasoning from prior knowledge I love coming to Hacker News to see. You're right. Thank you for the extra bit of gym motivation.

[deleted]

Re: Daily energy expenditure through the human life course

#226

Post by tonyedgecombe »

hombre_fatal wrote: post #98
dijit wrote: post #31

Earlier quoted context omitted.

I think thats basically true for most people, hence the belief that metabolism slows with age. Proving that its not metabolism would imply that our weight gain in later life is a combination of other factors. I would bet good money on the increase in sedentary leisure activities, the reliance on motorised vehicles and a lack of energy to be active. I would bet on those long before anything as nebulous as diet or inta…

I can think of two major, extra lifestyle factors that increase calories in adulthood that we overlook in favor of more appealing explanations like "metabolism tho": 1. We eat out more as adults. Our skinny kid/teen selves didn't even have the money/vehicle/norm to eat out much less do it daily like we can as adults. This also includes eating out during our lunch break. Every time we eat out that's an easy 1000+ calo…

Alcohol consumption is probably in there as well.

Re: Daily energy expenditure through the human life course

#227

Post by alexfoo »

tomjakubowski wrote: post #181
alexfoo wrote: post #177

Earlier quoted context omitted.

Strava’s calorie estimation is awful. Depends on the elevation gains in your 100km ride but I think that 3,300kcal for a 100km/4h ride is generous. 800kcal/hr is hard work and keeping that up for 4h is even harder. 25kph does not sound like 800kcal/hr unless there was some reasonable elevation gains. I’d expect at least 1000m elevation gain over that 100km for those numbers to at least approach something sensible. If…

I am also very skeptical of Strava's caloric estimates but: > I’d expect at least 1000m elevation gain over that 100km 1% average grade is pretty mild. I'd bet OP did at least 3000m to get those numbers

It’s 2% average grade if you finish at the same elevation as you start.

Re: Daily energy expenditure through the human life course

#228

Post by nradov »

blipvert wrote: post #223
nradov wrote: post #142

Earlier quoted context omitted.

That seems high. Someone your weight would generally only burn about 750 kcal on that workout.

It’s what Strava says I’m burning so I can only go by that. 750 would still be above the low end of the range quoted by the OP. The amount of extra food I needed to start eating!

You shouldn't go by Strava numbers, they are known to overestimate.

Re: Daily energy expenditure through the human life course

#229

Post by jabradoodle »

missedthecue wrote: post #126
valec wrote: post #124

Earlier quoted context omitted.

activity levels almost certainly. uni it's not impossible you were walking over 12k steps a day. that's 3-400 calories over the average american's daily steps of 4000.

That's also completely canceled out by enjoying a single 32oz soda. Walking a lot and having a bad diet rarely even each other out. And it's so easy to cancel it out I don't think most people realize. A brisk 2km walk burns less calories than are consumed when eating two regular Oreos.

If you think drinking a litre of soda is no big deal I would encourage you to rethink. 400 calories with no nutrition is a lot.

Re: Daily energy expenditure through the human life course

#230

Post by cykros »

_Algernon_ wrote: post #141
MattRix wrote: post #133

Earlier quoted context omitted.

I wouldn’t be surprised if most thin people who claim to eat lots of junk food actually just eat a lot less regular food. In other words, they don’t eat many calories, but the calories they do eat are junk.

This. Plenty of times I've been to lazy to make dinner and ate 200g of chocolate and a coke in a single sitting.

I assume you mean a bar mostly consisting of dairy and sugar with a bit of chocolate -- making a meal out of actual high quality dark chocolate adds up, but can hardly be considered junk food. <3 my 90% dark Lindt chocolate bars -- between those and all the bacon I've been eating this year the pounds are falling off.
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