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Comment by Supersam654 | Hacker News Reader

Personally, I was more surprised by the various groups of people who _don't_ have higher metabolic rates:

> Children’s metabolic rates stay high until age 5, but the rate slowly begins to glide down until it plateaus around age 20. Interestingly, adult rates are stable until age 60, when they begin to decline. After age 90, humans use about 26% less energy daily, Pontzer says.

> The study also found that pregnant women don’t have higher metabolic rates than other adults; their energy use and calorie consumption scales up with body size

> The metabolic rate didn’t zoom up in hungry teenagers either

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This seems almost unbelievable to me. Almost everyone I know, with a handful of exceptions I can think of, had a dramatic change in what I can only say was metabolism at 30 declining steeply to 40. I can tell you personally my ability to lose weight when exercising daily has decreased significantly since 30. If it’s not metabolism, then what? Diet and exercise are almost identical.

You are probably consuming more calories than you think you are or not burning as many as you think you are.

I'll agree with that. There are certain lifestyle changes at that age range: office job, extra cash for eating out, etc.

Or you change jobs to one that gives you free snacks. Back when people worked in offices...

I can't say for the cases you named but its easy to overlook small lifestyle changes, like how much someone walked in college vs after. That was one shift for me.

Yes! I went from walking from home down to campus and then all around campus everyday. Plus I didn’t have much money for food. Lots of peanut butter and jelly sandwiches and noodles/pasta. Now, I drive everywhere and sit on my butt in front of a computer most of the day. Plus I can afford much more calorie rich food, and a lot of it. No surprise I’ve put on 40 pounds over the last 20 years since finishing college.

Stress

True, there are studies showing increased exposue to cortisol causing weight gain.

It's a combination of your lifestyle changing and your kidneys beginning to lose function. Your metabolic rate may be the same but your GFR is declining.

You’re onto something there. Folks 50 years ago on average lost a bit of weight into their 40s and 50s. Now they gain weight.

There’s something different about our environment.

Everyone[0] has a car, is sedentary, and has cheap, fast, and easy access to a huge variety of high-calorie foods?

[0] not literally

I think it was partially smoking, and not eating as much food. It seemed like everyone smoked 50 years ago.

(I don't know if people lost weight in their 40-50's.)

Metabolic rates (caloric intake and use) may be the same, but the bodily priorities for where those calories go may differ. That would be my guess anyway.

That might be the effect of long term imbalance of hormones.

Weight gain is long term, and a bad diet and/or feeding period take a long time to do their damage. Think one pound a year.

Anyway, I disclaim any particular medical or nutritional expertise.

> Anyway, I disclaim any particular medical or nutritional expertise.

Has anyone actually ever been sued on a forum for bad medical advice? That seems impossible when there are literal quack colleges in the US.

Disclaiming expertise doesn't have to arise out of fear of lawsuits. It could just be letting people know as a friendly gesture that you're not an expert and that your comment may reflect a layperson's best understanding rather than specialized education in the field.

Without more details if be inclined to blame "almost identical" as the culprit (not an expert):

Making all your meals 5% bigger would cause a weight gain of nearly 10lbs/yr, and the kind of switch in diet that can happen naturally with age (especially including eating out more with friends) can make it hard to spot incremental changes.

Moreover, a lot of exercise doesn't actually do much for weight loss (it's still immensely beneficial for your health; please don't stop). To counteract the aforementioned 10lbs/yr you'd have to walk an extra ~20 minutes per day. It isn't all that much per se, but if your exercise were 20 minutes of something high intensity and an hour of something low intensity every single day (a lot more than most people get) it'd still be a noticeable demand on your time -- enough that I don't think you'd call the extra exercise level "nearly identical."

It's also possible less visible culprits exist if you're used to average weight gains/losses of under a pound per month as a function of your diet/activity. E.g., iirc fidgiting and tapping your feet consumes nearly a pound per month in calories, and that doesn't seem like the kind of thing you'd recognize stopping/starting over a timespan of decades.

Exercise isn't always aerobic. Resistance and weight training which causes a muscle buildup can help you lose weight because your Total Daily Energy Expenditure (TDEE) increases while you build more muscle.

Now if you combine aerobic and anaerobic training strategically, while you have your eating habits checked, you can lose that quarantine weight in no time. This is what i am doing now.

Sure. I’ve got about 20lbs more muscle than I did at 30. I currently lift 3-4 times a week and run 3.5+ miles 5-6 times a week. At 30 I worked out or ran 3 days a week.

I eat out less now and generally pay attention to what I eat vs just eating whatever is in front of me. Nearly identical meaning proportions are the same but I eat less junk food now.

I was a college athlete, but there’s no way I carried the fitness forward ~6 years without maintaining my college level of workouts.

I realize it’s all anecdotal, but based on my personal experience, the study is really tough to take at face value.

People tend to massively overestimate how much the extra muscle mass matters, and how much they burn during exercise, though, and it takes very little to overcompensate with a little extra food here and there.

I lift too, and for many years I wrote down everything I wrote, and weighed myself every morning. I could tell very precisely how much I burnt, and it tended to shock people on lifting forums who were certain they needed to down lots protein shakes to get enough calories.

At my peak lifting I wasn't huge, but I was around qualification levels for competitive powerlifting for my weight class at the time (I squatted about 200kg, benched 150kg), and exercised 5 days a week.

I burned about 2000kcal/day on average. I tested that many times when bulking or slimming down by seeing how much I needed to increase it or drop it down. And it changed a little as I added muscle, but much less than you might think.

I'd have people arguing with me on fitness forums that there was no way I was burning that little, and that I really needed 3000kcal/day or more, and then complain about why they were adding weight.

People in a more active job would burn more than that, and people with a more active life outside of work and the gym as well, but people are notoriously bad at estimating their activity levels and apply calorie level assumptions that are often many decades out of date and based on far more labour intensive daily lives. Basically the only way you'll know is to track and measure.

At rest, muscle only burns about 8 kcal/day/kg more than fat.

I'm curious: how tall are you and/or roughly how much do you weight? Benching 150 kg with 2000 kcal/day absolutely does sound odd compared to recommendations. However, my personal experience also tells me that the regular recommendations might be a bit high.

6'1/185cm. At the time my weight was around 93kg, so 150kg bench was nothing special for my size. When bulking I'd do about 2400kcal. For people pushing towards competitive levels it may well have made sense to go higher to allow exercising accordingly harder, but for me it was just to stay fit so I prioritised staying reasonably lean.

Also worth mentioning that outside of lifting my life absolutely was/is very sedentary, so I did burn less than a lot of people.

EDIT: One thing that will confuse people here is that style of exercise will matter a lot. To reach a 1RM of 150kg on bench meant most of the time I did bench 1-2 times a week for 5 sets of 5 reps of ca 120kg or so. My bench routine took 10-15 minutes. My whole lifting program took about 40m x 3 days/week. I added some cardio to that, but that is not a lot of physical activity. Someone who does bodybuilding on the other hand will typically do a lot more volume.

Yeah whenever I’ve trained for marathons and I’ve not actively worked at keeping myself from eating too much more, I’ve gained weight during the training. Every single time. You do of course burn more calories than you would if you didn’t exercise but most people don’t realize how easily you can eat back those calories and more if you’re not careful.

> Without more details if be inclined to blame "almost identical" as the culprit (not an expert):

Why? I mean, why do people find the idea of older people needing different diet due to body changes related to age so unbelievable? There are many changes related to age - how quickly injuries heal, how quickly you recover from something physical or tiring, how much or well you sleep. Your heartrate is slowly changing with age too.

Why would it be shocking that these has also impact on how food affects your look?

> To counteract the aforementioned 10lbs/yr you'd have to walk an extra ~20 minutes per day.

That is not how this works tho. The effect of exercise is not just in how many calories you theoretically spent running/walking exactly same distance. Your body adjusts to exercising way more - including on metabolism and body temperature. It has impact on how body works overall including on hunger - depending on exercise it can go both toward eating less or eating more. It has impact on how many muscles you have, how much energy you burn while building those muscles etc.

Experience of "I stopped exercising and keep eating the same, I gained a lot of weight" is not rare.

> Experience of "I stopped exercising and keep eating the same, I gained a lot of weight" is not rare.

It's not rare because calories add up immensely quickly. Say that you were burning 200 kcal per day exercising - and that is a low estimate. If you keep eating the same, you end up keeping 6000 kcal per month more - that translates to 1.7 lbs of body weight - per month. So, 20 lbs in the first year!

So the claim is, that simultaneously: 1.) when you stop exercising, it does a lot for weight. 2.) If you start exercising, it does nothing for weight loss.

>1.) when you stop exercising, it does a lot for weight.

Yes, if you also don't downsize your meals at the same time. Which a lot of people don't.

>2.) If you start exercising, it does nothing for weight loss.

Yes, if you increase your food intake because you feel more hungry, which a lot of people do. If you keep eating the same -- then it of course has a noticeable effect.

For exercise to matter in your weight loss, you have to always keep in mind your food intake. It is still very beneficial and should not be ignored!

> Why?

Because it's much more likely that they're one of the <nearly everyone> who can't estimate calories in/out well than that they're an outlier with a significant metabolic drop in some small number of years, especially given that small misestimations are large enough to yield the observed behavior. Maybe there's something else going on, but "without more details" it wouldn't be the first place I'd look.

> older people needing different diet

Absolutely! I hope nobody took away opposing statements to that from what I said. The double whammy of needing fewer calories and being less equipped to absorb vitamins and whatnot necessitates a significant change in diet with age. I was only commenting on this one person's experience aging just a few years in the middle of their life.

> walking

> That is not how this works tho.

Especially for walking, that's exactly how it works. Walking builds negligible muscle mass, and everything else you've mentioned (aside from perhaps impacts on hunger), adds up to well under a 5% error in calorie estimates -- well under the noise floor from applying a general purpose calorie estimate to any one specific person.

For me, 5% larger meals just means 5% more poop

While there might be a very small decline in resting metabolism, most of those people are delusional. They overestimate their exercise and underestimate calorie consumption.

I recommend that everyone get an occasional resting metabolic rate test. It's an easy non-invasive test which uses your exhaled gasses to calculate your daily calorie burn. Most people who claim they can't lose weight due to a "slow metabolism" actually have a totally normal metabolism.

https://www.dexafit.com/services/rmr-metabolic-test

I suspect many people making that claim don’t want to learn that they have a normal metabolism.

I think I could have this conversation with people of many ages. For me my mid 20's was when I started to notice more weight gain. I've put it down to now working an office job where I am sitting most of the day, as opposed to standing up and walking around in retail. My job is also more stressful which has led me to be less active after work as I just want to "relax" when I get home.

I have no doubt this also means I eat slightly worse food or larger portion sizes. Luckily I've noticed it and started to make lifestyle changes to prevent it further.

I also noticed the same in many people, as well as myself. And I do not think the other commenters are correct in their explanations.

At least in myself, I can clearly see that in my 20s I had a much more sedentary lifestyle, sitting in front of a computer a heck of a lot more, having less social life and eating _much_ worse (processes food, sweets, coke) and still being able to maintain a normal BMI.

If its not metabolism it must be some other mechanisms that allows people to do it, but metabolism seems the simplest one.

hormone changes? so how energy is spent building cells changes?

My anecdata is the opposite.

I track calories/food quality, weight, plicometry, and exercise (although not all of them all the time). With precise and systematic measuments, I find easily that it's a matter of food quality, quantity, and exercise.

I'm convinced that there are several external factors that make people over 30 gain weight, more than metabolism: work, children, stable relationships and independence.

I also used to think that teenagers are fit without any effort, but if I look at them, this is generally not true. I will start believe people who claim that it's a matter of metabolism when they'll start to track food, weight and plicometry, and will go on a sports (not walking) regime. But not before.

I have this 'theory' about 'diet fatigue': the more times you lose weight, the harder it will be the next time. I hadn't associated it with age but with the count of times I (kind of successfully) lost weight through calorie deprivation and sometimes additional physical exercise.

I have this pet theory as well, at least for myself. After being quite sick for 3-4 weeks at 28yo and losing 12-15 lbs, I noticed that since then, my energy levels never returned and my ability to lose weight changed from pretty easy to needing to exercise and diet quite a bit.

Insulin resistance slowly builds up with age.

Not sure I noticed anything like this myself. I did see however, around 30, a massive change in work/life balance.

I went from a rather care-free person in my twenties, who took all vacation days he could, worked part-time for stints in junior functions, to becoming a manager and working 55 hour workweeks and less vacation. That tripled my disposable income and reduced my free time by a third.

My caloric intake before this had been somewhat restricted by these two factors: not enough money to have 'eating out multiple meals daily' be an affordable habit. And not limited enough in time to make that habit-of-convenience a necessary one.

Now I can both afford it and time-wise it helps not to have to prepare every single meal anymore. But for my caloric intake this new habit doesn't help.

We're not talking about massive changes here, but even a 5% increased daily intake stacked over the course of years adds up.

Not to mention changes in non-base metabolism caloric expense. Spending so much time on an office chair definitely leaves less time to move the body. Lots has changed about my behaviour. e.g. in my twenties I often spent two nights a month dancing from 1am till 5am, nowadays I'd still go out but it'd be more of a pub-setting, sitting & drinking.

So I do see changes, but I wouldn't necessarily relate them to base metabolism rates. In your case diet and exercise are almost identical but it definitely wasn't for me.

Like most things there's quite a lot of factors to play into this but I would say one of the main factors here is that generally men start reducing natural testosterone production and gradually losing muscle mass sometime after around age 30. Basically, the more muscle mass you have, the more calories you burn to maintain it.

Also to compound this your metabolism tends to adapt to whatever you are doing. Even if you are doing lots of exercise, your body does tends to become more efficient at doing that exercise, using less calories to do the same thing over time. The same is true of running on lower and lower calories, your body adapts to run on less calories so it actually helps to do something of a 'bulking' period every so often to keep your metabolism running at a higher rate and not letting it drop down to 'economy mode'.

If you change nothing from your 20s to 30s, keeping exactly the same calories in your diet and same amount of exercise then you will most likely start to gradually gain a calorie surplus from this loss of muscle and thus start gain some more fat from the excess calories. You'll basically need to reduce calories or increase exercise to compensate.

Also look into what you can do to help maintain/improve your natural testosterone production (better sleep, nutrients like zinc and magnesium etc) as this will help offset it to some degree (poor sleep alone will absolutely destroy your natural testosterone levels). Alternatively you can look into Testosterone replacement therapy, which seems to be quite common these days.

It can't be testosterone alone. I've got the levels of a 25 year old according to my urologist (and yes, he sent me to be checked for anomalies) and I've noticed a significant decline in metabolism after the age of 40, despite exercising and not gaining weight and sleeping more than before. My (unscientific) hypothesis is that it's mostly a mental thing due to work/life being less demanding at this point.

Efficiency adaptation to exercise is mostly a myth. It happens only slightly for runners, and hardly at all for cyclists.

That’s because nobody knows anything about how our bodies burn energy, just like the article says, and the use of the term metabolism is complete pseudoscience to convey a misunderstood abstract concept.

Yes. Broad claims in biology and to the left in this xkcd are super suspect.

https://xkcd.com/435/

I don't think diet and exercise levels "are almost identical".

I have realized that the only physical "exercise" that gets easier by the day is eating.

> Diet and exercise are almost identical.

What about everyday motions? At 50, I push myself gently up from my chair, while 25 year old coworkers leap up. They walk faster, they simply move with more energy through the day. Such things add up over the course of a day/week/month/year/decade.

They do, and I've lived that. Sincere advice: force yourself to stand up without any assistance from your arms. I had a knee issue for a couple of years, and got into that very habit -- at first out of necessity. Before long it was required. It took about a month (!) to build back up the core strength to stand normally again.

Your core strength will decline quickly, and soon you will have to help yourself up all the time. Don't let the slide happen.

I think being moderately poor really helps with staying thin. A major shift for me going towards my 30s was replacing parties with dinner dates.

Last year during the short lockdown break I went to a birthday party followed by a rave followed by sleeping on a friend's couch followed by a walk of shame home... Like in the good old days. My Garmin said I did 30k steps that night, probably double my previous record. I also couldn't really eat much for two days after that, so there's that too...

It does make sense if you think about it in terms of overall calories consumed rather than metabolic rate.

Children are very small and light, so even with a higher metabolic rate they need less calories overall than an adult. However a teenager is usually reaching adult size, but still with the same higher metabolic rate as the child, meaning they will need more calories than a typical adult who is on a lower metabolic rate even at similar size, that is why teenager seem to eat so much.

Pregnant women likewise may not have a higher metabolic rate, but they still need to eat more calories overall then before they were pregnant as they are growing in size and weight. It's not much different to a bodybuilder eating more calories to build then maintain a greater muscle mass.

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