[tails4e]

I've always been curious about my own metabolism. When I was a teenaeger / in university I ate pretty badly. Chocolate bars every day after lunch, loads of carbs, not to mention alcohol, etc etc. I was rail thin. I once got a body fat assesment when I joined a gym (I did no exercise at all and this was a brief attempt to get buff) and the person doing the test was shocked and couldn't pinch anything to measure. I had no fat. This lasted till I was 25 where seemingly overnight I then had to watch what I eat or I started to gain fat. So what explains this seeming inability to gain weight no matter what I ate, and in my mid twenties having a more normal response to junk food?

[djtango]

How much "passive activity" were we doing back in the day?

So as a teenager, I was carrying 5-10kg of books and walking back and forth between classes every 40 mins.

As an undergrad I was travelling across campus multiple times a day, spent hours on my feet in labs, did multiple heavy grocery shuttles and also spent a lot of time partying.

In my first job, I was still getting up 5-6 times a day for meetings and had a decent walk/cycle built into the commute. but in my first remote job, I could be sat in the same spot for 8-10 hours without moving. And because I wasn't drinking water I wouldn't need to go to the bathroom... /facepalm I'd also be so engrossed that sometimes I'd forget to turn on the lights...

So even though I do more than an hour of intense exercise a day, my activity outside of those exercise hours has cratered from when I was a teenager and was constantly running around.

[shapefrog]

So as a teenager, I was carrying 5-10kg of books and walking back and forth between classes every 40 mins.

As an undergrad I was travelling across campus multiple times a day, spent hours on my feet in labs, did multiple heavy grocery shuttles and also spent a lot of time partying.

In my first job, I could be sat in the same spot for 8-10 hours without moving.

A year in to my first job I had added 15kg (~30lbs ~2stone) - while consuming way less food and alcohol than my university days.

[sn9]

I actually lost weight upon entering college because my campus was so large that my physical activity increased from when I was in high school.

[riazrizvi]

I understand that as a healthy body sustains lifestyle damage, the effects begin to stack up, and then the effects become more noticeable, but it's not age based because it's reversible.

So look to your unhealthy lifestyle's accumulated effects in your body, atherosclerosis, obesity, pre-diabetes, hypertension, specific nutritional deficiencies, physiological mental health... And make a robust effort to improve your lifestyle, and you'll start to feel like you did, 10, 20 years ago.

Speaking from personal experience, I'm 50ish and after getting a health scare which triggered me into aggressive corrective action a few years back, I've overcorrected. My allergies have ameliorated back to old levels, I can drink beer again, and I can recover from a night out like I used to be able to in my 20's, I'm able to maintain a serious athletic schedule. Obviously most of the time I now eat really well, but my body's youthful tolerance to harm has been recovered.

[djtango]

Would love to hear what sort of things you did as part of your intervention?

Def noticing amongst my friends a few new allergies/intolerences manifesting as we get older

For some context am reasonably healthy and actually had to increase my sodium intake because I had over corrected on reducing salt consumption and was getting hyponatremic after training

[riazrizvi]

A good story is Rich Roll’s Finding Ultra. Or a good technical read on nutrition is Julia Ross’s The Mood Cure. But I read about 50 non fiction books cover to cover each year, and learning about your health is a big area, made harder by the reality that for every good book on the topic there are 19 others that are bad. There are lots of bad fads and actors, and they can include pill pushing doctors, sadly. The only real way to figure out how to get healthy is to experiment until you succeed at it. I guess one piece of specific advice I’d give, is if you have long term high cholesterol, and high blood pressure, take your doctor’s advice and take a statin if they recommend it. I think that was a huge boost. Also, when you want online advice on health, add ‘site:.gov’ to your search so that you get good sources and not health blogs.

Ultimately I think you’ve got to come up with a good model of your physiology based on uncontroversial science. So in the case of your training, you’d figure out you are draining yourself of more than sodium chloride but rather the broad spectrum of minerals that you typically sweat out, so your ‘salt intake’ is a multi mineral supplement and not actual salt. Which is what I imagine you figured out.

[MichaelDickens]

In addition to activity levels, you probably just weren't eating that much food. It was similar for me when I was a teenager: some days I would binge on a ton of junk food, but other days I would forget to eat breakfast, and the latter happened often enough that I stayed skinny.

[naijaboiler]

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

[Loughla]

I had to supplement with calorie shakes for workout guys in my 20's, just to maintain weight. I ate trash, and a shit load of it. And that's not considering the amazing levels of calories I would've consumed from alcohol.

Same activity level now as then. But now if I think too hard about a candy bar I gain weight that never goes away.

[willcipriano]

> Same activity level now as then.

As you go from untrained to trained you burn less calories doing the same activity.

[bennyelv]

It's actually nowhere near as simple as that, and it depends on how you define the "same activity".

Moving your body from one location to another at a particular speed results in a fairly static amount of work done (in the basic physics sense). So if the same you hops on a bicycle and cycles up the same hill in the same conditions with the only difference being that one of you has trained hard for the last 5 years and the other hasn't (but somehow your body mass has stayed the same) then you'll burn exactly the same amount of energy. Untrained you will find it much harder, but the energy burn will be roughly the same.

There are some things that can be different as you go from "untrained" to "trained", for example lighter people burn less energy moving themselves around than heavier people. Trained people tend to do activities harder/faster so the "same activity" could actually be a much harder activity despite it not feeling that way. Although if the activity involves travelling a set distance some of the extra effort involved in doing it faster is offset by the fact that it takes less time, so the difference between the two is not as large as you'd think.

[paulpauper]

same here. the hockey-stick or v-shaped weight rebound if I even deviate a tiny bit. amazing how fast weight comes back on.

[goostavos]

>I'm not misremembering

It's the easiest explanation. As a gym bro that regularly cycles weight, it's is remarkably easy over/under estimate intake just going off recollection. I always think I'm dialed in until I write things down (I'm almost always eating way fewer calories than I think).

[lkbm]

Okay, so just to be clear: the OP is describing a phenomenon that is extremely widely reported, and is doing so in discussion thread about study that also reports finding this phenomenon, and your claim is that the simplest explanation is that OP is misremembering, and the research is just wrong?

Do you have any evidence for this bizarre dismissal?

[scythe]

The study says that TDEE is generally constant from 20 to 60. Multiple studies have shown that on average people do a terrible job of estimating their food intake ([1], [2] for example), especially when they aren't actively monitoring it. Meanwhile the person you're talking about (who isn't properly "OP") is claiming that they ate more in their 20s than they do today without corresponding health effects. This is not consistent with TFA nor with previous research.

1: https://www.nejm.org/doi/full/10.1056/nejm199212313272701

2: https://www.tandfonline.com/doi/abs/10.1080/08870446.2019.16...

[goostavos]

(This thread is now hella old, but only look at comments every once and awhile, thus the late reply).

I'll just say the same thing I always say in these kinds of "who are you to deny science!?" replies. For everyone championing how hard, complex, and subtle weight loss is, there's a "dumb" gym bro just weighing him self every day and dialing back calories until the scale starts going in the right direction. It works every single time. 100% of the time.

[Jenda_]

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 article states that the basal expenditure increases with "fat free mass", so someone fat but muscular will have this "overheating" problem even stronger?

[naijaboiler]

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 economic meal i used to have. Working at mcdonalds and eating double quarter pounder meal + extra quarter pounder + shake is not something i can misremember. clearing a tub (not a pint) of ice-cream at a sitting is not something i can misremember. setting timer to dliberately eat 6 times a day all summer in order to forcefully gain wait, is not something i misremember. emptying an entire box of cereal in a sitting is not something i misremember. Eating 25 big wings to the bone at a sitting is not something i misremember. And i was all of 130lbs max. It really is insulting to suggest that the likely explanation is that I am misremembering.

In my 40s now, eating a lot is day like today when all I ate was jamaican takeout that i ate most of it. and that's on the high end of what i usually eat. i strictly drink water and black coffee, nothing else. my entire 20s was pop and juice. thats easily another 400 calories daily. I am 150lbs now.

[lkbm]

Skinnier would mean more surface area to volume, but less surface area total.

If we're just looking at energy in and energy out, it could partly be less thorough digestion. I wonder if there are poop studies that find more leftover fat or carbs in faeces of children.

[ashconnor]

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 you probably were eating as much as you think.

[eastbound]

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?

[tuatoru]

N=1, but visceral fat starts building up sometime after age 40 anyway. About 52, in my case.

[carstenhag]

Yeah, but likely you walked more. Cycled more. Ran more. Stuff like that.

[valec]

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.

[missedthecue]

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.

[MattRix]

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.

[_Algernon_]

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

[cykros]

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.

[glouwbug]

The American dream

[IsoldesKnight]

Pretty sure if it was the American dream, it would be 7oz of chocolate.

[_Algernon_]

I believe for this to be the American dream, you have to do this in addition to dinner.

[tails4e]

I would say this was partially true in my case. While I ate badly, I didn't eat huge portions regularly. I also didn't eat breakfast regularly then (and often don't now either). In college we got fish and chips takeaway once it twice a week,and while it was definitely the worst kind of junk, I would be full quicker than others. That said, I regularly put away a quarter pointer, portion of chips, fizzy drink and a cheese and onion pie (deep fried cheese basically, and amazing). And not an ounce of fat on my body.

[Fricken]

Strava tells me I burned 3,3000 calories this morning on my (4 hour)100km bike ride. About the equivalent of drinking 2 cups of melted butter, or eating 50 pounds of lettuce. When I'm doing exercise like that regularly it's hard to eat enough.

[alexfoo]

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 it was a flatter ride than that then Strava is just lying to you.

But, yes, long distance cycling is an awesome way of burning calories. When I used to do Brevet/Audax riding I was the closest to my old teenage weight as I have been in the last ~30 years.

[Jenda_]

Yeah, 25km/h requires less than 150W [1], so it's 600Wh total, the efficiency of human metabolism is about 20% [2], so it's 3kWh of total energy input = 10.8MJ = 2600 kcal. (I have been using generous estimates, so this should be an upper bound)

[1] https://en.wikipedia.org/wiki/Bicycle_performance#Total_powe..., https://www.road-bike.co.uk/articles/cycling-power.php [2] https://www.quora.com/How-efficient-is-the-human-body-at-con...

[bennyelv]

Given that we're talking about cycling, the solution is to buy a power meter and measure rather than estimate. Unfortunately that's a rather expensive option for all but the most committed cyclists.

Being someone who has a power meter, I can say that strava's estimates over a long time period aren't that terrible, but if you're riding in a group, or there was a some wind, or a million other reasons they can be absolutely miles out.

That's hardly strava's fault, it's more about what's actually possible with an estimate.

What is completely made up and should be ignored is the calorie burn estimates you get from gym equipment.

[throwaway2037]

    Strava’s calorie estimation is awful.

Re-reading your post made me think: I bet this is intentional design -- overestimate number of calories burned. Then, people will tell their friends about this amazing device from Strava that burns an unreasonable number of calories...

[tomjakubowski]

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

[alexfoo]

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

[ses1984]

That’s more than an order of magnitude more calories burned than walking 12k steps.

[missedthecue]

Humblebrag? Almost 100% of humans are incapable of doing a four hour 100km bike ride without a lot of prep and training. Nevermind doing this daily.

[Fricken]

A person who gets their doctor recommended 150 minutes of moderate aerobic activity each week shouldn't have much difficulty adapting their bodies to distance cycling well enough to hit comparable numbers after a handful of training rides. Elites can hold pace for those distances at 50 km/hr, which is faster than me doing an all-out sprint.

And one doesn't have to do 100km all at once. A 10km commute each way over a 5 day workweek is a much less intimidating prospect.

[0xfaded]

When I lived in Denmark I was riding 2x 5km to and from work. I then needed to start going somewhere ~80km away, and I was able to do it without special preparation. After a couple of times I was able to do it both ways in a day.

Now I live in America need a car :(

[Jenda_]

I also did a 65km and then 135km ride with similar "training" (2x7km four times a week to school), but it was way slower than 25km/h. They took 4.5 and 10 hours, respectively. I think riding 100km without training is possible, but at 25km/h very difficult.

> Now I live in America need a car :(

Why? Are there even longer distances?

[throwaway2037]

Why did you leave Denmark? A job? University? That sounds like a terrible trade for quality of life, including raising a family.

[bennyelv]

I think the numbers are more than you'd think - as a cyclist who's near the top end of "keen amateur" but still nowhere near what people are capable of at the elite level my experience is that anyone of moderate fitness can do a 4 hour 100k without too much trouble...

It could depend on how you define "almost 100%" of course. There's a big difference between 5% and 0.001%.

[jeffbee]

While true, the energy expense doesn't really scale with speed, so if a couch potato got up and decided to do 100k in, say, 8 hours, that's around the same amount of energy.

NB nobody would be able to do this without ingesting a substantial amount of food during. If you didn't start eating hourly after about 1-2 hours in, you'll "bonk" or run out of glycogen.

[nradov]

It really depends on how fat adapted your metabolism is. When untrained people exert themselves their muscles tend to produce most energy from glucose and very little from fat. By doing a lot of zone 1-2 training you can gradually shift your metabolism to rely more on fat, at least at lower effort levels where you're not limited by oxygen. This allows you to go longer than 2 hours without bonking.

[alexfoo]

It does depend on your conditioning though. When I did my first 200km ride I ate like a horse every 50km.

After a few years of regular (monthly) 200km rides I could do a 200km ride (~10h elapsed) without eating anything on the way round.

[tomjakubowski]

A lot of people could get there with like six months of not that crazy training.

Cycling at 15mph on flat ground is pretty easy. If you can do that for an hour, and can progress at 10% increase in riding time week over week (pretty reasonable for someone who is still gaining fitness from "nothing"), you'll be doing four hour rides after just 16 weeks.

[missedthecue]

I would categorize 16 weeks of training as a lot of prep

[paulpauper]

Strava is probably wrong. Even if it's right, it's not like this can continue forever. At some point, the weight loss will stop despite Strava showing a deficit. So either you have to eat less or exercise even more.

[lrem]

25km/h is the regulatory max speed of e-bikes around here and you averaged that. Most people would take years of training to get to the point of being able to exercise like this.

[carstenhag]

Really depends on the bike. It's way easier to achieve this on a racing bike than on a trekking/city/mtb

[tomjakubowski]

no, they wouldn't

[mathgeek]

While this is certainly an argument for “how do I lose weight” the relevant part here is that the asker wondered why they started gaining weight, which makes a reduction in daily calorie burn relevant if caloric intake remained roughly consistent. That is a lot of ifs, naturally.

[XorNot]

Could be a reduction in calorie excrement really - i.e. they just started absorbing more of it.

[mathgeek]

Could be any of a number of factors. No way to know.

[BobbyJo]

32oz is a ton of soda tho.. Even when I was a teen at 6'4", 32oz of soda would be a sickening addition to a meal.

[missedthecue]

Perhaps you're not American, but Gallup reports that among those who drink soda in the USA the average daily amount is 31.2 oz

[TeMPOraL]

32 oz, if I'm converting correctly, is a little shy of 1 liter. If so, that isn't a big amount really, especially daily.

[BobbyJo]

> among those who drink soda > average

Two factors in your statement that lead me to believe 32oz is still a boat load. What's median and 75th percentile? I imagine the distribution here is non linear across the soda drinking population.

[antisthenes]

Depends how it's measured.

16oz of store-bought soda is not the same as 16oz of restaurant soda, at least 30% of which would be ice.

I wouldn't trust Gallup to report with nuance.

[username135]

Thats so gross

[jabradoodle]

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.

[paulpauper]

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.

[nradov]

Walking is great for many reasons, but 10K steps isn't much. It would be silly to expect much weight loss from that. And most people significantly understand their caloric intake.

[tonyedgecombe]

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.

[Viliam1234]

As a student, I used a bus to get to school. As an adult, I walk by foot, more than an hour a day. Also, I didn't exercise in my youth, and I do now. Yet, it is now that I am fat.

[qingcharles]

I wonder about the same thing. I was a fat kid, but my best friend was so skinny. We would walk down town and he would stop several times to stuff chocolate bars in his mouth, and then buy two McDonald's meals. I would do none of this and our physical exercise was the same.

Then we went away to University and in his mid-20s the poor guy suddenly, almost overnight, put on a ton of weight.

[glouwbug]

25 is about the age you’ve worked a year two after an undergrad. More money means more desk work and more access (speaking funds) to eat out

[ianlevesque]

I had a similar trajectory. The transition from one to the other was a long course of antibiotics.