15 ms·

Daily energy expenditure through the human life course

247 points by shartshooter 3y ago

dfjkdksjds789 3y ago
Super useful outcome, especially given I find that people think that after reaching even young ages 24, 25 even begin thinking that metabolism has some extreme drop off right after reaching young adulthood
- LapsangGuzzler 3y ago
  It’s an inevitable outcome of a culture so focused on age. I watch twitch streamers in their 20’s talking about how they’re old already. Narcissism isn’t just a social phenomenon spread online, I think it actively contributes to many public health concerns we’re seeing today.
  - icegreentea2 3y ago
    I agree with your observation, but at the same time, I do think that what a lot of these people might be expressing is their observation of the disconnect between their socially implanted expectations (you're an adult when your 18/21! you are now -mature-), and their experience reality. Which is that for many (most?) people who go through the typical North American education pipeline through university/college (and I'm only making this limitation because that's my experience, and the experience of most of my friends), that looking back, they were definitely not "mature" at 18/21. They probably weren't even mature when they graduated undergrad or started their first full time job out of school. Everyone has a different point, but they typically recognize somewhere in their 20s that 'oh wow, we keep changing and maturing'. And the first, most basic way to express this observation is with a pretty crude 'oh wow I'm old'. I think eventually, most people can move beyond that first reflexive observation.
    - WJW 3y ago
      I some times make the following observation: When I was 15, I thought I had grown up quite a lot and looked back on my 10-year old self as someone who was just getting started. When I was 20, I thought I had grown up quite a lot and looked back on my 15-year old self as someone who was just getting started. When I was 25, I thought I had grown up quite a lot and looked back on my 20-year old self as someone who was just getting started. When I was 30, I thought I had grown up quite a lot and looked back on my 25-year old self as someone who was just getting started. Now that I'm 37, I think I have finally grown up and my 30-year old self was just getting started. But I recognize that my 42-year old self will probably look back on me and still see the same pattern.
      - deleted 3y ago
        [deleted]
      - datadrivenangel 3y ago
        6 years ago I was an idiot. 6 months ago I was an idiot. Last week I was an idiot. ... Glad I'm smarter now.
- icegreentea2 3y ago
  So the results show that on average, metabolism is stable from 20 years onward. That means that there actually is a drop from 18 to 25 (it's there for men at least when you look at Fig 2). Now think about where most people will be anchoring their perception of "adult" from (it's going to be some value in that range). That means that there will absolutely be plenty of people who experience a real decline in metabolism in the years following their "personal adult threshold". Now, that's a pretty small drop, so definitely the other life transition (probably starting an office job, living alone) will probably play an even larger part to any weight related changes. But even given a hypothetical case where someone kept the exact same activity level, the amount of metabolism decline over that period is probably small enough to delay the onset of any noticeable body composition change (like order of 10 pounds) for a few years, adding to the mid to late 20s experience.
- Jensson 3y ago
  Such rumors are created and spread by people who want an excuse rather than a solution. This wont help them since they want to cling to their excuses, but it can help others ignore those rumors.
  - Noumenon72 3y ago
    I found the misconception useful because it prompted me to invest time in improving my diet in my 20s, before it was too late. Even if my metabolism has stayed the same since then, the no-vegetables-or-fruits approach would have caught up with me at the same time "low metabolism" would.
- cmiller1 3y ago
  According to the paper this is "Fat-free mass-adjusted expenditure", and testosterone DOES start to slowly decline after around age 25. The trouble people have with starting to gain weight easier as they enter their 30s and 40s is caused by this since they'll lose muscle mass as such hormones decline, which causes fat gain assuming similar food intake and activity levels, this effect is not included by adjusting for fat-free mass.
  - SamoyedFurFluff 3y ago
    I also think 30-40 is more likely caused by life just being more complicated! Juggling kids is basically a full time job, and many families are two income families. Hard to hit the gym when your child, who cannot be left alone, increases your effective work hours to 80-90/week minimum no vacation no breaks.
- hotnfresh 3y ago
  Anecdata: I ate 3500-4000 calories a day of mostly junk in high school and college. I lifted weights some. I (barely) “had a six-pack”. No sports, only incidental cardio. Around age 21 or so, I decided to try to drop a couple pounds and make it a really cut six-pack. I ate a strict 1400 calorie diet (packaged food to make it easy, no cheating at all) for about three months. I started running a couple times a week. I’d reckoned this would only take a month or so. Found the calorie deficit pretty easy, actually. Three months in, the scale showed one pound of loss. Discouraged, I returned to my old eating habits. I immediately gained about 15lb. Had to drop soda completely to stabilize it (i didn’t drink much alcohol then). Slowly got worse through my 20s. By 30, not turning into a blimp required a careful diet. No more 4k+ calories of pizza, soda, and potato chips without (visible) consequence. My metabolism 100% for-sure changed in my 20s, a ton, not gradually. But I may have killed it, and perhaps I would have been able to keep doing what I was doing another couple decades otherwise (I would bet zero dollars on it, but hey, I guess the science disagrees, I just find it literally incredible)
  - SoftTalker 3y ago
    Teens are growing until early 20s that’s why they can and do eat so much. When you stop growing you enter into your adult metabolism. I started gaining weight/fat in my mid 20s and had to adjust my eating habits from what was normal in the preceding 8-10 years
    - hotnfresh 3y ago
      Sure, hgh+T is a hell of a combo, but TFA claims a gradual change from teen metabolism in one’s 20s. I experienced a switch-flip that cut north of a thousand calories of apparent metabolism in a matter of months.
    - paulpauper 3y ago
      but the article says it's gradual. gaining 20+ lbs in a year not gradual.
  - paulpauper 3y ago
    same here but at a later age this seems to agree with a lot of people's personal accounts. A switch is flipped in which the body for whatever reasons starts hording energy. maybe it is stress from family life or work related... who knows...The weight comes on so fast... it's nuts how much weight some people gain starting at 25 or so. Guys who were 130-180 lbs lean in college now 240+ lbs all a sudden at 30+.
meindnoch 3y ago
Another sobering result for the fitness industry, that convinces 30 year old men to be on TRT.
- reedf1 3y ago
  Convincing men at basically peak testosterone production to permanently impair their natural ability to produce it. It's awful. Not to mention the side effects of taking exogenous hormones e.g. damage to your liver...
  - wredue 3y ago
    I see a study suggesting that, in hypogonadal men (important), TTh or TRT seems to improve their liver.
  - tayo42 3y ago
    Peak? We're talking about 30 year olds. For some it's not really convincing. They look at it like doctor perscribed steroids.
    - deleted 3y ago
      [deleted]
    - deleted 3y ago
      [deleted]
  - diath 3y ago
    This seems to be contradicting your claim: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8451678/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8451678/
    - civilitty 3y ago
      Did you read the study? Or even the first line of the abstract? “Hypogonadal men with hepatic steatosis” is literally in the first sentence. It’s a study on men with low testosterone and fatty liver disease. They already have damaged livers.
dp-hackernews 3y ago
No mention of how a persons lifestyle changes over that period though. Surely there is a correlation to the causation? The head-bone is connected to the neck-bone etc... You cannot study figures in isolation and expect them to yield some meaningful results while ignoring the influence of other figures upon those results. - Kids move around a lot, and they're still growing/developing - Teenagers move more constructively i.e. sports, and they're still growing/developing - Adults move a bit less, and have almost stopped growing/developing - Older adults try do keep moving, but with other life responsibilities it gets hard to put the same time in - Older adults become less and less bothered about moving - Even older adults have acquired illness and injuries and can't move as much Seems quite simple and obvious no? - Maybe... Those that don't fit the mould have some other reason that makes then more of an outlier to the norm. If life today didn't offer as much assistance as the past, we would all be a lot more healthy - not to mention more active, you know walking and manual work etc... Not to forget that the abundance of food (good and bad) will have a bearing on the results. Maybe the older people that can't afford as much food are the outliers - and better benchmark. Unless you are suffering from malnutrition, or you are overeating the wrong sort of food (good and bad) then your metabolism, unless affected by biological factors should be pretty stable. Isn't this what being in homeostasis means? Doesn't the body adapt to effects of S.A.I.D. - Specific Adaptations to Imposed Demands.
- paulpauper 3y ago
  If inactivity was the explanation, it logically follows it would be possible to undo obesity by simply having people move more, but the evidence suggests exercise does not help compared to diet. https://cdn.vox-cdn.com/thumbor/U1RxtW9oglcck-2g2X_SrKzIA44=/0x0:1201x631/1120x0/filters:focal(0x0:1201x631):format(webp):no_upscale()/cdn.vox-cdn.com/uploads/chorus_asset/file/6398845/diet_JAMA_CHART.0.png https://cdn.vox-cdn.com/thumbor/U1RxtW9oglcck-2g2X_SrKzIA44=...
  - hombre_fatal 3y ago
    With no further context that graph is simply showing that exercise increases/maintains lean mass which will slow down absolute weight loss during a calorie deficit.
dp-hackernews 3y ago
Did anyone happen to read any of the responses to the article at https://www.science.org/ https://www.science.org/ It seems that others don't fully support their findings either. https://www.science.org/doi/10.1126/science.abe5017#elettersSection https://www.science.org/doi/10.1126/science.abe5017#eletters...
- medler 3y ago
  The only criticism I see is some nitpicking saying that the claim “was based on statistical means, ignoring the known intense drops in the energy expenditure that some individuals show during their life. For example, a clear decrease in metabolic rate is observed in humans that consume calorie-restricted diets (Fothergill et al. 2016), an adaptation named ‘metabolic slowing’ (Johannsen et al. 2012). Therefore, the statement is innacurate and possibly wrong.” These critics don’t seem to disagree with the core claim about average metabolism across the lifespan.
ermir 3y ago
This was completely expected, at the macro level this is easily observed by measuring the outputs of metabolism and bodily function, mainly heat and physical activity. All humans have a baseline bodily temperature, meaning that the inner metabolism also is the same across all humans.
- _Algernon_ 3y ago
  "Humans are spherical cows"
- a_cardboard_box 3y ago
  Your body can change the temperature gradient near its surface to retain or expel heat without a change in metabolism.
- paulpauper 3y ago
  metabolism varies greatly controlling for height, activity level, and weight . sometimes as much as 600 kcal /day
- cma 3y ago
  Sweating at different rates, surface blood vessel dilation including in your lungs, all change the flux. Having longer hair or wearing warmer clothing can too and can be balanced by those other things. Activity also gets balanced by those things. Eating cold food and drink vs warm etc. That we maintain a baseline temperature doesn't tell you that metabolism alone is all that regulates it, there are other factors.
smileysteve 3y ago
This doesn't seem to line up anecdotally; The first outlier I see is female health and PCOS, starting in mid 20s for women. The next outlier I see is insulin resistance and pre and diabetes based metabolism decline. From a hormone perspective, nose, ear, chin (femalr), and head hair seem to be going under significant change.
- fortran77 3y ago
  This is caused from eating too much, not a decline in “metabolism”
  - tristor 3y ago
    Insulin resistance and PCOS absolutely have effects on metabolism. It’s very well studied.
  - smileysteve 3y ago
    So, the combination of the research and my anecdotes - and your response seems to be That by our early 20s our metabolism has already slowed (sugary food, alcohol, precipitous drop in activity)
    - fortran77 3y ago
      No, our metabolism isn't "slow" (for 99% of people). People just start eating much more and moving much less.
- wredue 3y ago
  Mid 20s with when your lifestyle shift just starts to catch up to you. You go from a more active young person that eats just enough to get back to hanging with friends to binge drinking in an instant. Then you go from that to a much lazier, snackier lifestyle of 9-5. Yeah, people on the whole do get fatter in their 30s, but that’s very easily linkable to lifestyle.
- paulpauper 3y ago
  how many outliers or exceptions do you need before you can throw out the theory
dp-hackernews 3y ago
* Extreme events reveal an alimentary limit on sustained maximal human energy expenditure. "We compiled measurements of total energy expenditure (TEE) and basal metabolic rate (BMR) from human endurance events and added new data from adults running ~250 km/week for 20 weeks in a transcontinental race. For events lasting 0.5 to 250+ days, SusMS decreases curvilinearly with event duration, plateauing below 3× BMR. This relationship differs from that of shorter events (e.g., marathons). Incorporating data from overfeeding studies, we find evidence for an alimentary energy supply limit in humans of ~2.5× BMR; greater expenditure requires drawing down the body’s energy stores. Transcontinental race data suggest that humans can partially reduce TEE during long events to extend endurance." https://www.science.org/doi/full/10.1126/sciadv.aaw0341 https://www.science.org/doi/full/10.1126/sciadv.aaw0341
strangesmells02 3y ago
Anecdotally: I havent changed diet one bit, actually I eat way healthier than when I was younger. And still weigh much more than when younger.
- marcinostefano 3y ago
  Eating too much for sure. When younger average person spend more time outside, traveling more etc.
- dijit 3y ago
  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 intake volume.
  - Lord-Jobo 3y ago
    yep, so many people go from 10k steps a day in college to 5k in an entry level position to 1k in a desk role. for a 200lb 6 ft tall male, thats 3000 kcal burned a day to 2600, to 2300. 700kcal a day being a weight change total of around 1.5 lb a week when you consider days off.
    - reactordev 3y ago
      Multiply that by 15-20 years and you’re looking at a solid extra 200lbs you have. Naturally every 40 or so makes you look in the mirror, make some minor changes that last a year or maybe a bit more and it’s back to getting out from under the gelatin we’re packing onto ourselves. In order to really, truly, get a handle on your weight - you need to increase muscle mass, operate at a slight caloric deficit, eliminate excess calories, and forgive yourself. The easiest way to distract you from excess calories is by doing something that keeps you busy (and hopefully works those muscles). Bikes rides, hikes, climbing gym, treadmills, skating, skiing, walking at a faster than moderate pace, running, weightlifting, tree cutting, brick laying. People often get demotivated when they call it “working out”. Instead, just call it “working”.
paulpauper 3y ago
I ain't buying it. There is a replication crisis in the sciences, and it would not surprise me if this is wrong too, or at least that the results do not mean what they are purported to mean. I have read many personal accounts here and elsewhere of men who were able to eat a lot in their late teens, 20s, and early 30s, and then suddenly by their 30s gain a lot of weight despite not changing their lifestyle or diet much. Inactivity alone does not explain it. Consider for example Bill Gate...according to his resume, in which he lists his precise height and weight, in his 20s he weighed just 125 pounds. It's evident he has put on a lot of weight, all in his mid-section, well before he turned 60. His job literally entailed sitting at a computer all day coding. If anything, given his philanthropy efforts and retirement, he is more active now than he was in his 20s when working full-time at Microsoft. Is he eating more? I doubt it. For so many people, celebrities for example, a switch is flipped in which there is sudden weight gain after the age of 30 or so, like John Travolta, Stevie Wonder and others. Because celebrities are photographed, you can see the weight progression and the abrupt jump in weight. Even with money for personal chefs and trainers, not gaining weight is hard. I can personally attest that if I ate the same quantity of food now as I did at 20 I would gain weight, and no I'm not 60. And I am just as active , maybe more so. So yeah not buying this study.
- sacrosancty 3y ago
  [dead]
- hombre_fatal 3y ago
  > Is he eating more? I doubt it. So, four paragraphs all based on this assumption. Why couldn't it be the case that a 20yo obsessive computer nerd eats less than a lavish billionaire?
logicchains 3y ago
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.
- hiAndrewQuinn 3y ago
  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 3y ago
    [deleted]
- paulpauper 3y ago
  muscle burns very little calories, and even pro bodybuilders who have lots of muscle quickly put on fat off-season when not dieting. I don't think this explains it.
  - jayGlow 3y ago
    they put on fat because the body fat level they compete at is unsustainable for long periods of time. additionally gaining fat is unavoidable when trying to gain muscle past a certain point.
    - dp-hackernews 3y ago
      I would argue they are not "gaining" fat, rather they are "balancing" the amount of fat the body considers normative. Of course you can easily acquire more fat with an inappropriate diet consisting of too much sugar, but a healthy diet will see your body maintain the ratios that are optimal for your current requirements. It never ceases to amaze me that we think that we know better, and yet the human body, as with other animals etc, have been around for quite some time now. Even if we had all the data from the past that we think is important now, we still wouldn't know better. There was a post the other day regarding "The prosecutors fallacy" that might fit well with this sort of subject matter.
karmakaze 3y ago
This is interesting for me to see. For the longest while I was wondering why through my 40s and later I didn't seem to be hit with middle-aged weight gain, all while living my sedentary life in the computer chair. I wouldn't classify myself as average though, I've always had low heart rate/low blood pressure and low blood sugar. Swimming in salt-water is fun because I can float without much effort. I did notice a decline in metabolism/muscle mass in the past several years, so I took to walking rather than driving in the city/neighbourhood and eating more and regularly which seems to have brought my levels back up somewhat. Now I look like someone who only goes to the gym on leg days.
deleted 3y ago
[deleted]
tails4e 3y ago
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?
- valec 3y ago
  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 3y ago
    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.
    - mathgeek 3y ago
      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 3y ago
        Could be a reduction in calorie excrement really - i.e. they just started absorbing more of it.
0xDEAFBEAD 3y ago
What's the age at which anti-aging interventions are most impactful? I assume they don't help much when you're young, because you're already healthy as a youth. Presumably waiting until you're on your deathbed to start high-intensity intervals is not the best idea either. Supposing a person had a limited budget of "anti-aging firepower" in the form of pills, exercise, etc. -- what age would be most impactful to apply it?
- nradov 3y ago
  That is way too complex a question to answer here. If you really want to dig into it including exercise, nutrition, sleep, and medications then the new book "Outlive: The Science & Art of Longevity" by Dr. Peter Attia is a pretty good summary of what we currently know. https://peterattiamd.com/outlive/ https://peterattiamd.com/outlive/ I wouldn't think of this from a limited budget perspective. Much of what you can do is cheap or free. It doesn't cost anything to go to sleep earlier.
deleted 3y ago
[deleted]

247 points by shartshooter 3y ago

Super useful outcome, especially given I find that people think that after reaching even young ages 24, 25 even begin thinking that metabolism has some extreme drop off right after reaching young adulthood

LapsangGuzzler 3y ago
It’s an inevitable outcome of a culture so focused on age. I watch twitch streamers in their 20’s talking about how they’re old already. Narcissism isn’t just a social phenomenon spread online, I think it actively contributes to many public health concerns we’re seeing today.
- icegreentea2 3y ago
  I agree with your observation, but at the same time, I do think that what a lot of these people might be expressing is their observation of the disconnect between their socially implanted expectations (you're an adult when your 18/21! you are now -mature-), and their experience reality. Which is that for many (most?) people who go through the typical North American education pipeline through university/college (and I'm only making this limitation because that's my experience, and the experience of most of my friends), that looking back, they were definitely not "mature" at 18/21. They probably weren't even mature when they graduated undergrad or started their first full time job out of school. Everyone has a different point, but they typically recognize somewhere in their 20s that 'oh wow, we keep changing and maturing'. And the first, most basic way to express this observation is with a pretty crude 'oh wow I'm old'. I think eventually, most people can move beyond that first reflexive observation.
  - WJW 3y ago
    I some times make the following observation: When I was 15, I thought I had grown up quite a lot and looked back on my 10-year old self as someone who was just getting started. When I was 20, I thought I had grown up quite a lot and looked back on my 15-year old self as someone who was just getting started. When I was 25, I thought I had grown up quite a lot and looked back on my 20-year old self as someone who was just getting started. When I was 30, I thought I had grown up quite a lot and looked back on my 25-year old self as someone who was just getting started. Now that I'm 37, I think I have finally grown up and my 30-year old self was just getting started. But I recognize that my 42-year old self will probably look back on me and still see the same pattern.
    - deleted 3y ago
      [deleted]
    - datadrivenangel 3y ago
      6 years ago I was an idiot. 6 months ago I was an idiot. Last week I was an idiot. ... Glad I'm smarter now.
icegreentea2 3y ago
So the results show that on average, metabolism is stable from 20 years onward. That means that there actually is a drop from 18 to 25 (it's there for men at least when you look at Fig 2). Now think about where most people will be anchoring their perception of "adult" from (it's going to be some value in that range). That means that there will absolutely be plenty of people who experience a real decline in metabolism in the years following their "personal adult threshold". Now, that's a pretty small drop, so definitely the other life transition (probably starting an office job, living alone) will probably play an even larger part to any weight related changes. But even given a hypothetical case where someone kept the exact same activity level, the amount of metabolism decline over that period is probably small enough to delay the onset of any noticeable body composition change (like order of 10 pounds) for a few years, adding to the mid to late 20s experience.
Jensson 3y ago
Such rumors are created and spread by people who want an excuse rather than a solution. This wont help them since they want to cling to their excuses, but it can help others ignore those rumors.
- Noumenon72 3y ago
  I found the misconception useful because it prompted me to invest time in improving my diet in my 20s, before it was too late. Even if my metabolism has stayed the same since then, the no-vegetables-or-fruits approach would have caught up with me at the same time "low metabolism" would.
cmiller1 3y ago
According to the paper this is "Fat-free mass-adjusted expenditure", and testosterone DOES start to slowly decline after around age 25. The trouble people have with starting to gain weight easier as they enter their 30s and 40s is caused by this since they'll lose muscle mass as such hormones decline, which causes fat gain assuming similar food intake and activity levels, this effect is not included by adjusting for fat-free mass.
- SamoyedFurFluff 3y ago
  I also think 30-40 is more likely caused by life just being more complicated! Juggling kids is basically a full time job, and many families are two income families. Hard to hit the gym when your child, who cannot be left alone, increases your effective work hours to 80-90/week minimum no vacation no breaks.
hotnfresh 3y ago
Anecdata: I ate 3500-4000 calories a day of mostly junk in high school and college. I lifted weights some. I (barely) “had a six-pack”. No sports, only incidental cardio. Around age 21 or so, I decided to try to drop a couple pounds and make it a really cut six-pack. I ate a strict 1400 calorie diet (packaged food to make it easy, no cheating at all) for about three months. I started running a couple times a week. I’d reckoned this would only take a month or so. Found the calorie deficit pretty easy, actually. Three months in, the scale showed one pound of loss. Discouraged, I returned to my old eating habits. I immediately gained about 15lb. Had to drop soda completely to stabilize it (i didn’t drink much alcohol then). Slowly got worse through my 20s. By 30, not turning into a blimp required a careful diet. No more 4k+ calories of pizza, soda, and potato chips without (visible) consequence. My metabolism 100% for-sure changed in my 20s, a ton, not gradually. But I may have killed it, and perhaps I would have been able to keep doing what I was doing another couple decades otherwise (I would bet zero dollars on it, but hey, I guess the science disagrees, I just find it literally incredible)
- SoftTalker 3y ago
  Teens are growing until early 20s that’s why they can and do eat so much. When you stop growing you enter into your adult metabolism. I started gaining weight/fat in my mid 20s and had to adjust my eating habits from what was normal in the preceding 8-10 years
  - hotnfresh 3y ago
    Sure, hgh+T is a hell of a combo, but TFA claims a gradual change from teen metabolism in one’s 20s. I experienced a switch-flip that cut north of a thousand calories of apparent metabolism in a matter of months.
  - paulpauper 3y ago
    but the article says it's gradual. gaining 20+ lbs in a year not gradual.
- paulpauper 3y ago
  same here but at a later age this seems to agree with a lot of people's personal accounts. A switch is flipped in which the body for whatever reasons starts hording energy. maybe it is stress from family life or work related... who knows...The weight comes on so fast... it's nuts how much weight some people gain starting at 25 or so. Guys who were 130-180 lbs lean in college now 240+ lbs all a sudden at 30+.

meindnoch 3y ago

Another sobering result for the fitness industry, that convinces 30 year old men to be on TRT.

reedf1 3y ago
Convincing men at basically peak testosterone production to permanently impair their natural ability to produce it. It's awful. Not to mention the side effects of taking exogenous hormones e.g. damage to your liver...
- wredue 3y ago
  I see a study suggesting that, in hypogonadal men (important), TTh or TRT seems to improve their liver.
- tayo42 3y ago
  Peak? We're talking about 30 year olds. For some it's not really convincing. They look at it like doctor perscribed steroids.
  - deleted 3y ago
    [deleted]
  - deleted 3y ago
    [deleted]
- diath 3y ago
  This seems to be contradicting your claim: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8451678/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8451678/
  - civilitty 3y ago
    Did you read the study? Or even the first line of the abstract? “Hypogonadal men with hepatic steatosis” is literally in the first sentence. It’s a study on men with low testosterone and fatty liver disease. They already have damaged livers.

dp-hackernews 3y ago

No mention of how a persons lifestyle changes over that period though. Surely there is a correlation to the causation? The head-bone is connected to the neck-bone etc... You cannot study figures in isolation and expect them to yield some meaningful results while ignoring the influence of other figures upon those results. - Kids move around a lot, and they're still growing/developing - Teenagers move more constructively i.e. sports, and they're still growing/developing - Adults move a bit less, and have almost stopped growing/developing - Older adults try do keep moving, but with other life responsibilities it gets hard to put the same time in - Older adults become less and less bothered about moving - Even older adults have acquired illness and injuries and can't move as much Seems quite simple and obvious no? - Maybe... Those that don't fit the mould have some other reason that makes then more of an outlier to the norm. If life today didn't offer as much assistance as the past, we would all be a lot more healthy - not to mention more active, you know walking and manual work etc... Not to forget that the abundance of food (good and bad) will have a bearing on the results. Maybe the older people that can't afford as much food are the outliers - and better benchmark. Unless you are suffering from malnutrition, or you are overeating the wrong sort of food (good and bad) then your metabolism, unless affected by biological factors should be pretty stable. Isn't this what being in homeostasis means? Doesn't the body adapt to effects of S.A.I.D. - Specific Adaptations to Imposed Demands.

paulpauper 3y ago
If inactivity was the explanation, it logically follows it would be possible to undo obesity by simply having people move more, but the evidence suggests exercise does not help compared to diet. https://cdn.vox-cdn.com/thumbor/U1RxtW9oglcck-2g2X_SrKzIA44=/0x0:1201x631/1120x0/filters:focal(0x0:1201x631):format(webp):no_upscale()/cdn.vox-cdn.com/uploads/chorus_asset/file/6398845/diet_JAMA_CHART.0.png https://cdn.vox-cdn.com/thumbor/U1RxtW9oglcck-2g2X_SrKzIA44=...
- hombre_fatal 3y ago
  With no further context that graph is simply showing that exercise increases/maintains lean mass which will slow down absolute weight loss during a calorie deficit.

dp-hackernews 3y ago

Did anyone happen to read any of the responses to the article at https://www.science.org/ https://www.science.org/ It seems that others don't fully support their findings either. https://www.science.org/doi/10.1126/science.abe5017#elettersSection https://www.science.org/doi/10.1126/science.abe5017#eletters...

medler 3y ago
The only criticism I see is some nitpicking saying that the claim “was based on statistical means, ignoring the known intense drops in the energy expenditure that some individuals show during their life. For example, a clear decrease in metabolic rate is observed in humans that consume calorie-restricted diets (Fothergill et al. 2016), an adaptation named ‘metabolic slowing’ (Johannsen et al. 2012). Therefore, the statement is innacurate and possibly wrong.” These critics don’t seem to disagree with the core claim about average metabolism across the lifespan.

ermir 3y ago

This was completely expected, at the macro level this is easily observed by measuring the outputs of metabolism and bodily function, mainly heat and physical activity. All humans have a baseline bodily temperature, meaning that the inner metabolism also is the same across all humans.

_Algernon_ 3y ago
"Humans are spherical cows"
a_cardboard_box 3y ago
Your body can change the temperature gradient near its surface to retain or expel heat without a change in metabolism.
paulpauper 3y ago
metabolism varies greatly controlling for height, activity level, and weight . sometimes as much as 600 kcal /day
cma 3y ago
Sweating at different rates, surface blood vessel dilation including in your lungs, all change the flux. Having longer hair or wearing warmer clothing can too and can be balanced by those other things. Activity also gets balanced by those things. Eating cold food and drink vs warm etc. That we maintain a baseline temperature doesn't tell you that metabolism alone is all that regulates it, there are other factors.

smileysteve 3y ago

This doesn't seem to line up anecdotally; The first outlier I see is female health and PCOS, starting in mid 20s for women. The next outlier I see is insulin resistance and pre and diabetes based metabolism decline. From a hormone perspective, nose, ear, chin (femalr), and head hair seem to be going under significant change.

fortran77 3y ago
This is caused from eating too much, not a decline in “metabolism”
- tristor 3y ago
  Insulin resistance and PCOS absolutely have effects on metabolism. It’s very well studied.
- smileysteve 3y ago
  So, the combination of the research and my anecdotes - and your response seems to be That by our early 20s our metabolism has already slowed (sugary food, alcohol, precipitous drop in activity)
  - fortran77 3y ago
    No, our metabolism isn't "slow" (for 99% of people). People just start eating much more and moving much less.
wredue 3y ago
Mid 20s with when your lifestyle shift just starts to catch up to you. You go from a more active young person that eats just enough to get back to hanging with friends to binge drinking in an instant. Then you go from that to a much lazier, snackier lifestyle of 9-5. Yeah, people on the whole do get fatter in their 30s, but that’s very easily linkable to lifestyle.
paulpauper 3y ago
how many outliers or exceptions do you need before you can throw out the theory

dp-hackernews 3y ago

* Extreme events reveal an alimentary limit on sustained maximal human energy expenditure. "We compiled measurements of total energy expenditure (TEE) and basal metabolic rate (BMR) from human endurance events and added new data from adults running ~250 km/week for 20 weeks in a transcontinental race. For events lasting 0.5 to 250+ days, SusMS decreases curvilinearly with event duration, plateauing below 3× BMR. This relationship differs from that of shorter events (e.g., marathons). Incorporating data from overfeeding studies, we find evidence for an alimentary energy supply limit in humans of ~2.5× BMR; greater expenditure requires drawing down the body’s energy stores. Transcontinental race data suggest that humans can partially reduce TEE during long events to extend endurance." https://www.science.org/doi/full/10.1126/sciadv.aaw0341 https://www.science.org/doi/full/10.1126/sciadv.aaw0341

strangesmells02 3y ago

Anecdotally: I havent changed diet one bit, actually I eat way healthier than when I was younger. And still weigh much more than when younger.

marcinostefano 3y ago
Eating too much for sure. When younger average person spend more time outside, traveling more etc.
dijit 3y ago
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 intake volume.
- Lord-Jobo 3y ago
  yep, so many people go from 10k steps a day in college to 5k in an entry level position to 1k in a desk role. for a 200lb 6 ft tall male, thats 3000 kcal burned a day to 2600, to 2300. 700kcal a day being a weight change total of around 1.5 lb a week when you consider days off.
  - reactordev 3y ago
    Multiply that by 15-20 years and you’re looking at a solid extra 200lbs you have. Naturally every 40 or so makes you look in the mirror, make some minor changes that last a year or maybe a bit more and it’s back to getting out from under the gelatin we’re packing onto ourselves. In order to really, truly, get a handle on your weight - you need to increase muscle mass, operate at a slight caloric deficit, eliminate excess calories, and forgive yourself. The easiest way to distract you from excess calories is by doing something that keeps you busy (and hopefully works those muscles). Bikes rides, hikes, climbing gym, treadmills, skating, skiing, walking at a faster than moderate pace, running, weightlifting, tree cutting, brick laying. People often get demotivated when they call it “working out”. Instead, just call it “working”.

paulpauper 3y ago

I ain't buying it. There is a replication crisis in the sciences, and it would not surprise me if this is wrong too, or at least that the results do not mean what they are purported to mean. I have read many personal accounts here and elsewhere of men who were able to eat a lot in their late teens, 20s, and early 30s, and then suddenly by their 30s gain a lot of weight despite not changing their lifestyle or diet much. Inactivity alone does not explain it. Consider for example Bill Gate...according to his resume, in which he lists his precise height and weight, in his 20s he weighed just 125 pounds. It's evident he has put on a lot of weight, all in his mid-section, well before he turned 60. His job literally entailed sitting at a computer all day coding. If anything, given his philanthropy efforts and retirement, he is more active now than he was in his 20s when working full-time at Microsoft. Is he eating more? I doubt it. For so many people, celebrities for example, a switch is flipped in which there is sudden weight gain after the age of 30 or so, like John Travolta, Stevie Wonder and others. Because celebrities are photographed, you can see the weight progression and the abrupt jump in weight. Even with money for personal chefs and trainers, not gaining weight is hard. I can personally attest that if I ate the same quantity of food now as I did at 20 I would gain weight, and no I'm not 60. And I am just as active , maybe more so. So yeah not buying this study.

sacrosancty 3y ago
[dead]
hombre_fatal 3y ago
> Is he eating more? I doubt it. So, four paragraphs all based on this assumption. Why couldn't it be the case that a 20yo obsessive computer nerd eats less than a lavish billionaire?

logicchains 3y ago

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.

hiAndrewQuinn 3y ago
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 3y ago
  [deleted]
paulpauper 3y ago
muscle burns very little calories, and even pro bodybuilders who have lots of muscle quickly put on fat off-season when not dieting. I don't think this explains it.
- jayGlow 3y ago
  they put on fat because the body fat level they compete at is unsustainable for long periods of time. additionally gaining fat is unavoidable when trying to gain muscle past a certain point.
  - dp-hackernews 3y ago
    I would argue they are not "gaining" fat, rather they are "balancing" the amount of fat the body considers normative. Of course you can easily acquire more fat with an inappropriate diet consisting of too much sugar, but a healthy diet will see your body maintain the ratios that are optimal for your current requirements. It never ceases to amaze me that we think that we know better, and yet the human body, as with other animals etc, have been around for quite some time now. Even if we had all the data from the past that we think is important now, we still wouldn't know better. There was a post the other day regarding "The prosecutors fallacy" that might fit well with this sort of subject matter.

karmakaze 3y ago

This is interesting for me to see. For the longest while I was wondering why through my 40s and later I didn't seem to be hit with middle-aged weight gain, all while living my sedentary life in the computer chair. I wouldn't classify myself as average though, I've always had low heart rate/low blood pressure and low blood sugar. Swimming in salt-water is fun because I can float without much effort. I did notice a decline in metabolism/muscle mass in the past several years, so I took to walking rather than driving in the city/neighbourhood and eating more and regularly which seems to have brought my levels back up somewhat. Now I look like someone who only goes to the gym on leg days.

deleted 3y ago

[deleted]

tails4e 3y ago

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?

valec 3y ago
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 3y ago
  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.
  - mathgeek 3y ago
    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 3y ago
      Could be a reduction in calorie excrement really - i.e. they just started absorbing more of it.

0xDEAFBEAD 3y ago

What's the age at which anti-aging interventions are most impactful? I assume they don't help much when you're young, because you're already healthy as a youth. Presumably waiting until you're on your deathbed to start high-intensity intervals is not the best idea either. Supposing a person had a limited budget of "anti-aging firepower" in the form of pills, exercise, etc. -- what age would be most impactful to apply it?

nradov 3y ago
That is way too complex a question to answer here. If you really want to dig into it including exercise, nutrition, sleep, and medications then the new book "Outlive: The Science & Art of Longevity" by Dr. Peter Attia is a pretty good summary of what we currently know. https://peterattiamd.com/outlive/ https://peterattiamd.com/outlive/ I wouldn't think of this from a limited budget perspective. Much of what you can do is cheap or free. It doesn't cost anything to go to sleep earlier.

deleted 3y ago

[deleted]