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Comment by michalu | Hacker News Reader

Whenever there's insignificant science making "controversial" claims like "you can't lose weight with sport" journalist will provide storytelling instead of science.

The whole premise of that "You can’t exercise your way out of obesity" is that you burn more calories when you start running than later on as you continue. What's so controversial about it? It's normal that body optimizes for energy expenditure that's why we develop strength, endurance etc. And that's why when you're truly doing sports you're running more, faster, lifting more, etc. you increase the challenge to give your body greater burden to carry.

If I start lifting 20lbs and 3 years later I still lift that of course I won't lose weight.

You have that same thing in other disciplines - "historians" who can't make any meaningful contribution yet want to make name for themselves go on claiming "that or that king was gay" or "vikings were trans" or whatever fits the trending topics of the day and they get media exposure.

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> What's so controversial about it?

Your body burns incredibly more energy just "being there" than you burn moving about.

Exercise certainly increases your calorific expenditure, but it's much easier to ingest less fuel than to run 5 more miles because you had a portion of fries.

There are benefits in exercise, apart from the obvious ones the raising of the baseline metabolic expenditure, because muscles are expensive to maintain, but again, if you want to lose weight eating one less portion of fries is easier and takes less time than going for a 5 mile run.

> body optimizes for energy expenditure

No that's wrong, it optimises for energy maintenance. Genetically it's better to maintain fat and survive the next famine, than burning all the energy today. Which is why the body is so efficient at _not_ losing weight unless it has no other choice to maintain homeostasis. And thus to lose fat, we need to preferably eat less, not run more. Do both, and you'll do great.

While I agree with that excerice isn't a very efficient way to lose weight I think that you understate how many calories running burns.

When I run consistently I need to eat what feels like a lot more food to maintain my weight. Running burns about 700-800 kcal per hour for me (I have a quite small build) which ends up quite a bit over a week (I run 5-8 hours per week).

I have no clue how many calories running burns, but the act of moving around leaves you less time to eat :). Getting fat in the dark winters of Sweden is more likely for me, because I'm just bored and don't want to go outside as much so I sit inside and eat chocolate.

Think about it this way. The rate at which you burn calories is directly proportional to the rate at which you breathe out CO2 because that what happens with carbon you burn.

So if every day you train for an hour so that your breathing is 3 times faster, then you have additional two hours of burning in a day. 23 usual hours plus one worth 3. So you have 26 instead of 24 hours in a day.

It's way easier to put 15% less on your plate every day than to intensly train for an hour each day while keeping portions the same.

Yes but in numbers it is way more. If I bike for an hour I burn 700-1000kcal . Thats not 15 but 50% of the dayli calorie intake… i am no expert btw. My understanding is that the problem is more that after 20 minuts of sport, at a certain heart rate, is starting to burn fat…but not body fat. More free floating fat. And it takes one hour or so to start burning bodymass. So the fuel for one hour sport is what I ate before and not my bodyfat. Another example. I do mountaineering, mostly 1 week walking in the alps for 10h a day. Thats around 4000kcal more burned a day. And there I see instant results with all my friends coming with me . They get thin very fast. Around 500g of body mass a day :)

> If I bike for an hour I burn 700-1000kcal . Thats not 15 but 50% of the dayli calorie intake…

That's estimated and probably impossible.

1000 kcal is 4184000 joules, divided by 3600 it gives you around 1100W

Human at rest burns about 100W. Pro-cyclist can do additional 400W. There's no way you can burn energy at the rate of 1.1kW consistently for an hour unless you literally set yourself on fire.

EDIT:

I was wrong.

Apparently 700kcal burned per hour of cycling is a pretty realistic number. https://www.welovecycling.com/wide/2020/05/14/how-to-convert...

Also resting kcal burn might be around 1800 per day. So 40% increase in of calories burned by hour of cycling per day every day is achievable.

The question is how can you breathe out additional ~10h of CO2 within an hour?

3 times deeper breathes 3 times faster? Because that carbon has to go somewhere.

Cycling is only approximately 25% mechanically efficient, so the parent is correct. There's a lot of heat to get rid of.

Apparently 700kcal burned per hour of cycling is a pretty realistic number.

https://www.welovecycling.com/wide/2020/05/14/how-to-convert...

Also resting kcal burn might be around 1800 per day. So 40% increase in of calories burned by hour of cycling per day every day is achievable.

The question is how can you breathe out additional ~10h of CO2 within an hour?

3 times deeper breathes 3 times faster? Because that carbon has to go somewhere.

The CO2 concentration going up in the blood increases the efficiency of respiration (because it is ultimately diffusion).

You don't necessarily need to exchange 10 times the volume of air to deal with the additional CO2.

Range given for concentration of CO2 on exhaled air is 4-5%

So it looks like it could be 25% difference at most.

I doubt the 4-5% you saw is a first principle of breathing.

Why not? CO2 levels in blood must be tightly controlled. It probably can't get twice as high as usual.

If there's already 4% of CO2 in the air around you it's an immediate danger. While you can spend 10 minutes in 3%. If your body could bump up CO2 in exhaled air from 4% to 8% then you'd probably have bo problem surviving in air thay contains 4%.

Its a mix of anerobic and erobic exercis. Its hard to keep the same heart rate while biking. So sometimes the body doesnt need oxygen to burn fuel. So it doesnt exhale co2. As said I am no expert.

https://en.m.wikipedia.org/wiki/Anaerobic_exercise

That might be it. Thank you. If anyone wants to read more about it it's called Cori Cycle and it doesn't require oxygen and it doesn't produce CO2.

But you'll need to get energy eventually from normal beathing to recycle lactic acid back into glucose in the liver.

So probably after an hour of intense exercise you'll be breathing out more CO2 in the following hours as your body clears up lactic acid.

What's interesting is you get 2ATP from making lactate, but you need 6ATP to recycle lactate back into glucose.

Would that mean that for burning more calories you should have as much of anerobic excercises as possible because it's really ineficient use of glucose?

Thanks for the hint. I didnt know that one needs co2 to get rid of lactact

And to that question as said I am nonexpert. Imho sport after a certain (1h or so) time is a mix of both and should burn most calories in a healthy way. As far as I know there was a downside to having too much lactat. And burning calories aint synonym with burning body fat. Short intensity anerobic training is not atacking bodyfat in my opinion. It only uses the reserv in carbs we have anyway ( around 2000kcal) Biking is the best exercise for bodyfatburning in my opinion. If it is more than 2h.

If you are pro-athlete, I think you could, but 1kW is probably about max a human can burn for longer periods. I managed to output 500W for 5 minutes of rowing, but I'm overweight couch potato.

I think you need to account for human inefficiency. I have to burn more than 1 joule to output 1 joule on a bike. The average efficiency of a human on a bike is somewhere around 20 to 25%.

You are forgetting about the efficiency of the human body. Roughly, only 21% of your power is transferred to the bike. So a professional adding 400W to the bike is actually consuming ~1900W of power. This all matches up with their nutrition [1]. Namely

> They averaged 91 g of carbs every hour across all of the stages.

That's nearly 400 calories worth of sugar simply while riding the bike. In fact, I would say cycling is a clear counterproof of this article. Their equations are literally (calories in)*efficiency = power and they know exactly how much to feed. I don't disagree that 99% of people are better served eating less, but doing cardio for 2 hours a day + diet management will lead to very quick weight loss. "Very quick" here is 2lbs/week but people have some insane expectations.

[1] - https://www.welovecycling.com/wide/2021/07/01/how-much-do-th...

You are arguing a different point. They argued that doing exercise burns more calories than sitting idle.

@1_player said: > Your body burns incredibly more energy just "being there" than you burn moving about.

I was objecting to the word "incredibly".

You're assuming that breathing rate is proportional to CO2 breathed out, which I doubt. I barely breath any faster while running than while just sitting here, much less than 3x.

It is directly proportional because of how lungs work. The percentage of CO2 in exhaled air is roughly the same regardless of how fast you are breathing (if you don't artificially accelerate your breathing beyond what your body dictates).

Lungs can't put in more CO2 in breathed out air.

If you breath only slightly faster when you are running than when you are sitting that must mean you ran quite a lot and optimized your stride so that you don't burn much more calories running than sitting.

But more likely explanation is that you are not aware how fast exactly you are breathing when sitting and running. Try to measure it. Also take into account that you might be taking shallower breaths when you are sitting.

Just blow up a balloon when you are sitting and when you are running with your normal exhaled breath for few seconds to test it.

Also, you don’t absorb everything you eat. Actually, let me be clear: I have no evidence for this. But the fact that my weight is so consistent despite my radically inconsistent eating and exercising suggests to me that my body can regulate digestion. When I’m in a period when I’m overeating, my body just doesn’t absorb so much.

Again, more speculation, but i would imagine that metabolic disorders involve digestive regulation issues, not just lack of exercise and overeating.

TEE is what the article discusses measuring, not the energy burned during the exercises but the total in the day. The data in the referenced studies indicate the body compensates for the calories burned running by cutting back in energy use elsewhere.

The problem is, it isn't efficient if you are overweight :)

When I was at my heaviest weight, I could only do a normal-speed walk, which burned relatively little calories.

At my lightest, I was also having to go out of my way to eat extra calories, as I was cycling so much, and a fast 90 minute cycle would leave me light-headed if I didn't eat some extra calories.

This is primary that thing where exercising makes you more fit and in the long term more active in general. Because what was previously tiring straining activity suddenly becomes pleasurable. And if you eventually manage to stumble upon activity you actually like, it is way easier to do it then to sit at home hungry, passive and obsessed about how miserable you feel (until said person will break and eat a candy or something similar).

> Your body burns incredibly more energy just "being there" than you burn moving about.

Bullshit. My body goes through 1600-ish kcal on an idle day.

If I go out on a 4h steady bicycle ride (= 100km), I go through 2000 kcal on ride alone. That’s much more than my body burns just being there.

I don't get it, how is that a myth or controversial.

Cutting empty calories is the easiest to remove calories from daily total.

Exercise further decreases the ratio of calories in calories out.

Bottom line is: calories in - calories out.

There are caveats there for sure, like increasing muscle mass increases idle caloric burn. Different types of food have different effect promoting or impeding metabolism.

calories in - calories out was debunked a while ago. Different types of food and diet cause different degrees of weight gain or loss.

For an extreme example compare 100 calories of glucose to 100 calories of fibre, both are types of sugar. The fibre contains an extra electron that acts like a shell, and the body has to expend energy breaking that bond to make it digestible. So most fibre passes through you without affecting your weight.

The most useful measure of food is the Glycemic Load. Not Glycemic Index which is a measure of the net glucose in the food. Glycemic Load is a measure of how the body responds to the food. E.g. cold potatoes have the same calories and GI as hot potatoes, but their measured GL is actually lower, so cold potatoes are better for controlling weight.

> calories in - calories out was debunked a while ago.

Not really, it's just that calories-in is worst-case that's what's on the foods box, you cannot magically produce more energy but it's well known that not everything can be processed by the metabolism with the same efficiency.

So with extremes like your example the difference is naturally huge, but that doesn't matter in practice if one balances their consumption just somewhat it averages out and approaches something between upper (100%) and lower (0%) of efficiency, and in reality it rather close to the upper bound (averaged) as our metabolisms are quite efficient with the food most humans actually put into them.

Your glycemic index rule holds does not violate the calories in calories out rule, it's just more precise regarding the actual upper bound.

Not really. E.g. look at my second example, cold potatoes vs hot potatoes. Same calories, same exact ingredients, but hot potatoes are significantly worse than cold potatoes.

I dont have the link to hand, but there is a GL database maintained by Harvard, I think, that demonstrates this. I will look it up later for you.

It’s still calories in vs calories out. What changed is that our understanding of what determines calories in and calories out has become more nuanced. For instance, your examples

My examples demonstrate that calories in / calories out is false. I don't quite get your point? A calorie is a measure of the useful energy released from burning stuff in a furnace. It was invented to compare the efficiency of different fuels for steam engines. It has no relevance to humans, who don't use a furnace and steam power, but a complex chain of cascading chemical reactions.

What I mean is that "calories in" is not literally calculated by the total energy you put in your mouth, but rather the energy your body absorbs from that. And as you note that might be different based on the food, how the food is prepared, content of the food, etc.

Likewise "calories out" is not literally calculated by adding up your movement & exercise. We know that things like hormonal levels, etc can all impact how much energy your body is expending.

> calories in - calories out was debunked a while ago.

No, it wasn't. It's the generally accepted model of human weight gain. It's what most scientists who study this topic believe to be true. (And really, it's the only model that makes any sense, and is incredibly easy to test)

They only people who disagree with this model are considered to be outside the mainstream of science. They might be right (I don't think so though) - but it's certainly not debunked.

Obviously if you eat fewer calories than you burn, you’ll lose weight. But the inverse is not necessarily true. It’s possible to consume more calories than you burn and still lose weight, because your body doesn’t necessarily utilize all calories consumed.

Just because the USDA is 30 years behind the science doesn't make them right. There are hundreds of studies now debunking it. Do you really want to contend that 100 calories of fibre is the same as 100 calories of glucose? Ridiculous. In fact, the calories model never had broad academic support. Ansel Keys research is a joke today.

>The fibre contains an extra electron that acts like a shell, and the body has to expend energy breaking that bond to make it digestible.

I'm not a nutritional expert, but...this sounds like bro science. Do you have a source for this, or can someone who knows this better speak to it?

Not sure about exact process. But whole fruit has dramatically lower glycemic index than juice of the same fruit.

Guess what else has massive effect on metabolism? Exercise.

Also, various workouts have a lot of other important effects. Increasing bone strength, improving body resistance to inflammatory processes, developing micro vascular system… simply managing calorie in/out ratio won’t get you any of this. And dropping weight in a dumb way may do more harm than good.

Did you read the article? because this specific thing is what the science that the article covers explains.

tl;dr: your body burns roughly the same amount of calories regardless of exercise. However, it allocates those calories differently: if you don't spend them on exercise then it will spend them on stress (and presumably other stuff).

Which totally makes sense as to why my depression & anxiety fade if I run or work hard.

Depression and anxiety fades because endurance exercises release certain hormones and help to flush out kortizol.

And yes, it allocates calories towards building fat. Which is a weeeee different from burning them.

> your body burns roughly the same amount of calories regardless of exercise

Can you explain how this makes sense?

Different physical activities (running vs. sitting, for example) require different amounts of energy to perform. Calories are a unit of measurement for this energy. It sounds like you (via referencing the article) are claiming that a human will expend the same amount of energy in a given period of time regardless of their physical activity.

Even different workouts have very different calorie outcome. E.g. running at steady pace burns more than bicycle riding at steady pace at similar heart rate.

sorry, I was afk.

Yes, that's exactly what the article is saying. If you burn calories doing exercise, the body will spend less on stress response. But if you burn less (or none) on exercise, then it will spend more on other things, eventually coming to roughly the same calorie expenditure (as they measured). Which is why exercise helps with depression - your brain has less calories available to spend on stress responses and generally messing with your mood.

You really should read the article.

"If I go out on a 4h steady bicycle ride (= 100km), I go through 2000 kcal on ride alone."

What do you mean 'on that ride alone', are you doing more than 4 hours of excersise a day, every day? Because that's like 0.1% of the population, most can't even fit that in their diary, let alone have the stamina/etc.

Average bloke goes to the gym for an hour couple times a week, at that level you calorie consumption is basically unchanged - its withing an error margin of natural variability of food you eat.

I used to ride amateur cycling races, then just do a nice amount of rides/runs.. Now I'm in situation where time outside the house is hard to manage. I try to cut the calories, but weight keeps growing and overall health decreasing. Looking forward to stabilising family circumstances to have time to head out enough...

From what I observed myself, cutting calories is very difficult and result is miniscule. Adding some cardio (2h/week? 5h/week?) helps so much more and allows more flexibility with food. Also cutting calories does not help to increased overall immunity. Cutting calories is hard on mood (as in, no sugar high and tasty foods are limited) yet exercising allows to keep tasty foods AND gives runner's high. Win-win...

As for tight schedule, I don't believe in gyms. People waste so much time driving to/from favourite/affordable gyms... Running right out home and doing body-weight exercises at home would be both more beneficial to one's health and cheaper.

P.S. I mean regular non-exercise day is 1600kcal. 4 hours ride would be 2000kcal. So exercise day would be ~ 3400. Obviously it long-ride is weekend affair. Then one or two run 10k runs or quick 1h ride (another 1k kcal each). So ideally it adds +500kcal/day. And a lot of cardiovascular health. Well, it was 2 years ago before kid was born... Now it has a loooooot of variation.

> If I start lifting 20lbs and 3 years later I still lift that of course I won't lose weight.

This example is kind of bad :-)

You don't lose weight by lifting weights, in general.

And amusingly, if you did want to lose weight by lifting weights, your example is precisely how you <<would>> lose weight. You lift 10kgs over and over and over again, or even better, incorporate the extra weight into some sort of cardio routine.

Instead of increasing the weight, you'd increase the reps or the motion you use for lifting weights.

This is not accurate, weightlifting with a reasonably difficult weight for your strength level is one of the most effective ways to burn calories.

> This is not accurate, weightlifting with a reasonably difficult weight for your strength level is one of the most effective ways to burn calories.

It wont make you loose weight however. It will likely make you gain weight as your muscles will grow. Which is explicit goal of many guys who start lifting weights.

True, but for many people "lose weight" is really code for "lose body fat", since that has desirable health and aesthetic benefits.

No, it won't, unless you are eating excess calories. It takes a lot of energy to repair muscles and grow them.

Muscles weight more then fat. This is something that easily and regularly happen. I am not even saying it is bad thing to happen.

I think that this depends on your training regimen. You can train for strength, not muscle mass. This is especially important for some athletes, like cyclists, where extra weight is a liability (more mass for the same force means less acceleration).

When the gyms closed for the pandemic, I lost 5 kg of muscle. After coming back, I started doing fewer sets and have not regained the muscle mass. But my strength (the amount of weight I can lift) is now very close to pre-pandemic levels.

Isn't it anaerobic exercise, though, and from what I remember to lose weight you want aerobic exercise?

Thats correct. Yes it burns much fuel but also the wrong one

I'm confused. I'm being downvoted but you're saying I'm right?

Lol I dont know why. Okey one can loose weight with anerobic exercis but it should be way less imho. Because it takes time to start loosing bodyfat. There is the freely accesible energy storage first. To deplet them one needs time. Hmm the difference is between fat burning and bodyfat burning

Not on time. You cant lift weihgts for hours. But riding a bike or running goes for at least an hour. Golf burns a lot of calories because it takes 3 hours to complete. And lifting weight is also the wrong „zone“ for burning fat. It only burns avaible sugar. And to have that much fuel one needs to eat much ….

It is accurate. He didn't use the phrase "burn calories" at all ;)

Btw as far as I know the only way to burn bodymass with sports is to have a heart rate of 120-140 for at least one hour. And then it starts. And to loose one gramm of fat one needs to burn 4kcal ( it takes 4kcal to generate the fuel from the body. Fat has usualy 8kcal). Also to loose around 200g of bodyfat a day one has to run at least 2 hours. ( with 500kcal/hour burned)

You burn bodymass by spending more energy than you intake. Lifting something very heavy a few times will take a lot of energy and if you do a few sets the muscles will need repairing before they can work optimally again, which means your body will use energy doing this for the next couple of days. Overall a lot of energy used.

The scenario was "20lbs for 3 years".

Most "standard adults" (e.g no injuries, obesity or illnesses) would not consider 20 lbs "difficult", to start with. And especially not after 6 months of regular practice.

I used to think this too, it's a popular talking point in favor of strength training.

But as far as I know it's wrong.

A one hour session of strength training will involve some amount of work, and a lot of rest. Compared to doing cardio, where an hour of work is an entire hour of elevated energy expenditure, you're effectively burning a lot less during strength training.

In addition, the "after burn" effect is very minor (in the extra tens of calories only range).

I'm pretty sure you have that backwards. What you're describing is effectively trying to turn weigh-lifting into cardio, while most research shows that interval training / weigh training are more effective at burning calories than steady-state cardio.

One does not only lose weight because of the exercise itself, but by retaining muscles since they are a major calorific expenditure factor. Large mass muscles burn calories e.g. glutes

Sadly, muscle only burns 12.6 kcal / kg /day at rest [1]. If you put on an impressive 20kg of muscle that would only increase total expenditure by 250 kcal a day. If you want your muscles to burn calories, you'd better be exercising them.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2980962/

> If I start lifting 20lbs and 3 years later I still lift that of course I won't lose weight.

I don't understand, your body optimizes, and uses 20% less energy. However, you are still using the 80% which is more than not doing anything at all don't you?

Plus at least for running you can just run faster and make up for that 20% effioency gain. I personally do not think excercise is very good for losing weight but that particular argument is BS.

> Whenever there's insignificant science making "controversial" claims like "you can't lose weight with sport" journalist will provide storytelling instead of science.

I think this is quite the claim, maybe you should provide some evidence. I think it sounds reasonable to assume that those that lack the scientific basis will use storytelling to convince, because they have nothing else. But I'm not sure about the reverse.

Here we have storytelling, but the story is peppered with some data from experiments that support the claim. So how does storytelling imply lack of evidence?

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