> 2) Your hunger will increase to compensate for the calories burned and you'll subconsciously eat more if not carefully tracking.

This is also a oft-made claim that doesn't have much backing. Part of the point of the research described in TFA is that humans who face specific periods of energy expenditure during the day may often simply reduce energy expenditure during the rest of the day so that TEE remains roughly constant.

I know many endurance athletes (having been one) who would report that some levels of exercise actually result in appetite suppression.

I know this isn't rigorous but it definitely matches up with my personal experience -- I'll be hungrier, often ravenously so, after strenuous activity.

I have no apetite at all after biking for two hours. However, if I drink any diet soda or piece of candy with sweetener, I will be ravenously hungry in 10 minutes. Has always been like this so I stay away from that stuff.

My exercise is a game called Turf. Mostly played in Sweden where there are a lot of zones close by. I bike quite relaxed for 1-4 minuts and stand still for 20 seconds in the zone, then repeat until next zone. It's a bit harder during winter with all the snow though. I have done nothing to my diet and lost about 20 kilo the last year. The GPS says I traveled about 3500 km the last year at my slow pace.

100% this for me. I do intermittent fasting and my first meal is around 2pm. I do brazilian jiu jitsu around 6-9 and skip dinner. When I come home Im not hungry at all for at least an hour. Ill get a little hungry and if I eat or drink anything, the floodgates open and I cant stop eating. It is better to go to sleep a little hungry.

I try to have a 500 calorie deficit. If I have more than about 500 (say 1000) Im fine that day, but the next day Im ravenous and tend to overeat.

Oof this was me yesterday. Ate one large meal and snack between 2pm and 5pm because I had a work event in the evening. Got home around 9:30pm and really wanted to eat something and I almost did.

Drank a few cans of seltzer and wound up staying up doing emails and chores until 2am. Woke up at 9am today and I'm feeling a bit hungry at 11:20am, but even if I eat something now, it will be a net negative compared to what I would have eaten last night.

After a long bike ride, apart from being much hungrier than usual, food tastes better. Mediocre food becomes good, good food becomes the best thing you've ever eaten.

Yeah, that's the way I've felt when I've gone for a hike. The food tastes better and I will happily eat an amount of food that I later regret.

The activity makes a big difference for me though. Running for example tends to not have a major impact on appetite.. sometimes I feel like it actually lowers my desire to eat. That's based on relatively short runs though (45-90 mins of activity). I don't know how I'd feel after a marathon.

If I ride a bike for 3 hours, I feel like I could eat a horse.

This matches my experience. Swimming or biking makes me hungry. Running a reasonably long distance (say, 7+ miles) makes me a slightly nauseous and not hungry at all. Maybe it's because running causes more jostling and/or beats up non-muscle parts of the body more?

I have a bias towards the idea that we are very different, and it really depends on many unknown factors that apply only to one specific individual.

I also have that gut feeling, mind the pun. It stands to reason to me that since metabolism is incredibly complex, any slight variation in any of the parameters can lead to significant differences observed at an overall operational level. It's also very obvious people are reporting a wide range of experiences for the same activity

We're not _that_ different. And a lot _is_ known. There isn't anyone on earth with incurable obesity.

I know, anecdata, but on my off dates (I go swimming in the early morning three days a week) I have to fight not eating breakfast early and then needing lunch and dinner in the evening.

On my swim-days I have no problem with a late breakfast leading me to be able to skip lunch and enjoy my dinner.

But I have no other insight as my own experience.

It has a lot of backing when you look at people changing jobs without gaining or losing weight. We think of exercise in terms of X minutes on a treadmill, but people working long days of physical labor can more than double their daily caloric needs and will eat accordingly without prompting.

There where plenty of old jokes about lumberjack breakfasts and people eating skills tall stacks of pancakes. These guys weren’t trying to gain or lose weight just keep going for another day of hard labor, but when you start talking 6-8,000 calories per day it’s an insane amount of food.

Also, some of the feedback mechanisms involved are quiet slow and can take weeks to kick in. Your body doesn’t need to balance things every day as gaining or losing significant weight takes time.

Also anecdotal, but I’m not an athlete (like, the inverse of an athlete, I’m overweight and don’t move enough) and moderate exercising does, in my case, suppress some appetite. I eat les after exercising.

My 2 cents theory is that it suppress the "stress induced" appetite.

It might also increase dopamine. I have ADHD and there are two things that let me focus better and feel less hungry: stimulants and exercise.

Oh ! I have ADHD too so maybe it’s that.

If you are low on sugar (therefore hungry) for a while, your body will start burning fat (lipolysis) to restore sugar levels. This will suppress apetite.

It's easy to experience, although it can take longer for lipolysis to start if you're not used to. Of course, eating sugar during or before exercise delays it.

Some levels, yes, appetite-suppressing. When appetite returns, it can be with a vengeance.

I think it depends heavily on what you do. When you run, you tend to eat less, me definitely. When you weight lift, do body weight exercises, do anything that builds muscle, you need to eat. Personally I get more hungry about HIIT too.

And that additional eating is not a bad thing either. It is body needing supply to build muscles. For most beginners, that is a good thing.

Yeah, this is me. I naturally eat a lot less when I am exercising than when I am not. I'll often exercise in the morning and then have no desire to eat until dinner time.

If you fall into a routine CICO isn't that difficult in practice. First, while sleep/stress definitely impact the equation unless you are at an unusual life crisis, the ups and downs mostly balance out over time. Second, I don't recommend counting calories, at least not in the traditional way.

Instead, eat a fairly standardized diet at least on a weekly basis, so roughly the same meals (doesn't have to be exact). Eat a quantity of food such that you neither gain nor lose weight over a period of time (a couple of weeks with daily weigh ins is sufficient to ensure a flat line on a chart). Adjust intake until the line is flat if you start seeing a trend up or down. Now, to lose weight simple subtract 500 calories per day from what you eat (if you eat packaged foods, assume an extra 20% from the calories on the label). You should now have near exactly 1 lbs. per week weight loss. The reverse also works if you want to put on some weight. I do each of these once per year as a "mini-bulk" and a "mini-cut". I track my weigh ins on my Fitbit - it is a near perfect diagonal trend line over the 2-3 month period I do this.

NOTE: It is important to weigh in daily (at same time - I recommend first thing in morning after flushing the system) precisely because your weight fluctuates on a day to day basis by 2-3lbs. It takes a few days of weigh ins to see a trend change on the graph and you need to be able to adjust your intake if you are off.

Based on your description, I will venture a guess that you are not obese / grossly overweight. There is good evidence from various studies that obese/overweight people are not typically able to achieve this - usually their craving for food is far too powerful to just control simply by falling into a routine; or, the body sometimes finds other ways to adjust (the lipostat model).

This is really the problem with CICO - it is definitely correct in an abstract sense (weight doesn't come from thin air, and neither does food you eat magically disappear), but the factors controlling calories in and calories out are far more complex. Human behavior is far from being entirely rationally determined. Our choices (particularly in regards to food, exercise, and other basic needs) are to a great extent controlled by our metabolism, even though it often doesn't seem that way.

This probably explains why people rarely lose weight on the long term - you can allow yourself to be forced to eat less than your body thinks it needs for a while, and obviously you'll lose weight; but you will go right back up to your "normal" weight as soon as the forcing stops (program ends, willpower exhausted etc).

the type of food definitely matters. Carbs somehow 1) dont fill you up 2) spike your appetite. When I do low carb I feel so much less hungry on lower calories.

The deficit cant be too large, for me 500 is ok, but 1000 has me ravenous the next day.

Lots of obese people easily lose 2 pounds/week but as you get closer to a healthy weight it gets harder.

CICO was the first time I was able to actively lose weight in my entire life.

The general observation from most long-term clinical studies of obesity, as far as I understand, is that many types of diets work to reduce weight in the short term, but the weight almost invariably comes back after the intervention period ends (usually within 1 year or so after the initial weight loss). Conversely, people who are normal weight and are forced on a hyper-caloric diet for a limited time (say, a few weeks) will gain weight as expected, but will naturally lose it back over the next period without explicit effort.

This has generally been treated as a lifestyle issue, but another possibility gaining traction is that "obesity" is a disease in itself, one that tricks your organism is seeking to maintain excessive weight, by impacting your appetite, BMR, exercise habits etc; this will of course usually make people suffering from "obesity" (for lack of a better name) over-weight, but the weight can be controlled without curing the disease. Basically losing weight doesn't cure your "obesity", just like when you suffer of diabetes, controlling your diet keeps you healthy without curing your diabetes.

The possible causes of this "obesity" disease could well be diet related, and definitely refined sugars seem to be at least a major culprit.

Correct, temporary diets don't work. You have to change your lifestyle/diet permanently. This means after weight loss, you need to adhere to your new caloric intake baseline, which will be _lower_ than when you started. The more you lost, the lower it will be. This is hard, but not impossible to do. I can't speak for the obese because I was never there, but I was solidly overweight and proceeded to dump 40 lbs a decade ago, and never gained it back. Had I gone back to my pre loss diet it would have all come back.

NOTE: Before someone points it out, this is NOT incompatible with my parent comment. Going on a 500 cal/day cut and losing say 8 lbs will not lower your caloric baseline all that much, so temporary more or less works fine. If you use the same method to dump 40 lbs, you will need to readjust your baseline when done or you absolutely will gain it back as your caloric intake needs have been meaningfully reduced.

I have also done almost exactly this process, and it worked for years to regulate my weight. But then I hit a plateau (a high plateau, not a low one) where I was unable to drop weight no matter how low I cut my calories. I started at a range that I knew had worked in the past, and lowered it over the course of weeks, well past the point where I was miserable. I even tried more complicated things, like varying my intake, doing on weeks and off weeks, etc. Nothing worked.

I wasn't sure what was causing it, so I hypothesized that I was low on muscle mass, and took up weight training. Then I gained ten pounds.

I'm not sure what the upshot is here, but my guess is that this approach indiscriminately consumes lean muscle mass if you don't pair it with muscle-building exercises.

> But then I hit a plateau (a high plateau, not a low one) where I was unable to drop weight no matter how low I cut my calories.

Fat cells "remember" their metabolic environment when they were created--ie. they "remember" your weight and fight you when you try to reduce it. It's one of the problems with dieting to large weight losses.

It is somewhere around 3 years for a fat cell to die off and be replaced. You probably need to "hang out" at the plateau weight for a bit until the fat cells that remember you being heavier die off.

I thought you never lose fat cells, they only shrink? Got a citation for that assertion?

It's been a while. IIRC, it was from an article discussing the fact that radioactive fallout allows critical measurements of cellular lifetimes and that in about 25 years the fallout levels will be too low to do the experiments. I'll see if I can cough it up.

Sorry, medium link: https://prosetech.medium.com/what-nuclear-bombs-tell-us-abou...

> The carbon-14 fat-cell study also revealed that fat cells don’t last forever. Fat or thin, your body replaces roughly 10% of your fat cells every year. If you have more fat cells to begin with, you’ll have more fat cells to replace.

I can't seem to find the study talking about how fat cells remember the chemical environment when they are created.

Interesting, thanks for the links and info!

What I know from personal experience and learned a bit through knowledge osmosis (my better half studied ecotrophology/nutrition) is that many people underestimate how the body adapts to a "new normal" of caloric intake when this is well below basal metabolic rate/consumption.

On the other hand, the body also likes to get essential amino acids, if it does not get them from food, from the body's own muscle mass. This leads to a reduction of the own muscles and to a low basal metabolic rate.

I cannot judge whether one of the reasons is true, that would be the job of a good (!) nutritionist. Unfortunately, at least in Germany, the term is not protected and anyone, regardless of education, knowledge or experience may call himself so. Here there are really (especially on social networks) really many false claims.

The most likely possibility is that you were simply underestimating your calorie consumption. A lot of people forget to count the creamer in their coffee, the candies from the office break room, the little tastes while cooking dinner. Unless you have a severe metabolic disorder your body will only burn lean muscle mass as a last resort when you have exhausted glycogen stores and can't sustain the energy demand from fat alone. Some weight training is always a good idea, though.

I explicitly overshot the goal by more than 500 calories. Yes, there are always mistakes in estimation, but that isn't what was happening. Remember, I've done this before successfully.

A catabolic state induced by caloric deficit will absolutely consume lean muscle mass regardless of the availability of fat reserves. Muscle stimulus (via weight training, for example) and sufficient dietary protein can prevent this. But if you're just dieting without specifically controlling this, you will lose muscle along with the fat.

I've only used this to go up/down +-10 lbs seasonally (although I did permanently drop 40lbs on a one time calorie restriction diet about a decade ago, but not exactly this method). One thing to keep in mind (you probably thought of this already) is your calorie burn goes down as you lose weight. So a 160lbs person takes in less calories to maintain even weight than a 200lbs person, thus you may need to reassess baseline for longer cuts. Beyond that, no idea, and yes, everyone is individual.

I will say the whole time I have used this I have trained with weights extensively (5 days/week standard 3x sets per exercise body building routine). I do not know how much or little this plays into it, but definitely helps with the fat/muscle ratio (obviously).

I don’t see how the weight change is relevant in this. Muscle weighs more than fat, so your strength training caused you to build up some muscle, making you heavier. The valuable metric to track would be what % of your body is fat mass vs. muscle mass

For how long were you in a deficit before plateuing? There are some adaptations the body will make with regards to the thyroid that'll drastically lower your BMR

> Now, to lose weight simple subtract 500 calories per day from what you eat

I appreciate you are trying to be helpful. But most of what you said assumes a certain level or privilege (resources time/money/ableness) that the vast majority of people don't have. People working long hour jobs, or double jobs, or balancing kids/parent responsibilities. Often fast food is the only obvious option, and people aren't buying it until well into the throws of a low blood sugar event.

This coupled with metabolic/genetic differences can really muck up any given diet. What works of you doesn't just not work for everyone, it isn't even possible for everyone to follow.

That said, I know you are being helpful - my words or more to help those that might read them and be saying: "I did all that and it didn't work!"

> assumes a certain level or privilege (resources time/money/ableness) that the vast majority of people don't have

Unless you're talking about extremes (e.g. non first-world country, homeless, or disabled people etc) I'm going to call BS on this.

Everyone eats, and everyone has 24 hours in a day.

I don't know about the rest of the world, but in Australia you can buy a 800g can of tomatoes for $1.50, a 185g can of tuna for $1.60 and 1kg of rice for $1.40.

You could cook that up on a stove (with just a couple portions of rice) in about 30min, giving you two nutritious meals for (I'm going to be generous) let's say about $4. That's $2 per meal. 3 meals a day gives you a total of $42 for food per week.

So are you telling me that fast food costs less than $50 per week, that 23 hours isn't enough time left in the day to do everything else, or am I missing something here?

We once, out of pure interest calculated based on nutritional value, the cost of eating on different diets. We took the average discount market shopping cart, a conscious version, the same for a regular (so more pricy) supermarket and did a comparison with ecological as well as regional food sourcing.

Based on nutritional value (taking into account to fulfill the base needs as well as potentially overshooting on salt, fat, sugar and other things like Vitamin A just to name an example) we found that industrial food is always the more expensive solution.

Yes you can feed people on a very cheap industrial diet but they will miss essential nutrients as well as overshoot on salt, sugar, and others to detrimental health effects.

If you want a balanced diet mostly locally and seasonally produce (with added stuff like olive oil and such) cooked by yourself was way more cost efficient per nutritional value.

The problem is, that it takes time to learn this, especially to learn this from experience. Also time to relearn how food really tastes without added aroma and stuff. Time to learn how to cook efficiently and with variation. And so on. We don't learn this anymore. Not from our parents, nor otherwise. But the advertising tells us how easy it is to just open a fully ready meal, pop it in the microwave and be done in 3 minutes.

Instead of enjoying the quality of preparing food together as a family/couple. Spending time, experiencing the smell of fresh cut food, herbs and so on. We nowadays equivalent cooking to a chore.

I meant resource in the form of time/money/education/motivation.

If it were as simple as you say, then why (in Australia) is your minimum wage so high? So 2 hours of work on minimum wage can cover a week of food? And you are calling BS on what I said? Okay.

Fair point, and and definitely some truth to that. I almost added "This works for me, your mileage may vary" disclaimer.

I will say that what I said above is _relative_, so if you go out for fast food "more than you should" than that becomes your baseline. Anything can be a baseline, even if not a healthy one.

I also know at least one person who has tried it and swears up and down it just doesn't work for them.

> Often fast food is the only obvious option

Ironically fast food often has some of the most easily available calories and macronutrient ratio. Working out the calories and macro for a home-made meal can be much more time-consuming

Sure fast food is convenient if you have little time, but people have survived poverty and mental health issues long before it.

> measuring calories out is extremely difficult unless you're willing to live in a sealed room that monitors your exhaled CO2 24/7

Is even that sufficient? Like, would you be able to tell the difference between "oxidation done by the body to generate energy for human cells" and "oxidation done by bacteria that feast on calories your human cells didn't get"? Maybe you could tell by the mixture of other gases, but I suspect CO2 itself wouldn't suffice.

Yeah, that's a very good point. This is kinda getting off into the weeds from the original point, but interesting weeds nonetheless :).

This study[0] says that measuring CO2 is not enough, and that indirect calorimetry is the gold standard for measuring energy expenditure (EE).

"Calculated EE based on CO2 measurement was not sufficiently accurate to consider the results as an alternative to measured EE by indirect calorimetry. Therefore, EE measured by indirect calorimetry remains as the gold standard to guide nutrition therapy."

Google says "Indirect calorimetry is the method by which measurements of respiratory gas exchange (oxygen consumption, V O 2 and carbon dioxide production, V CO 2 ) are used to estimate the type and amount of substrate oxidized and the amount of energy produced by biological oxidation."

So getting back to your point, if bacteria are feasting on part of the calories and producing CO2, it seems that it would throw off the results even using indirect calorimetry. At that point though are we kinda arguing semantics? While our microbiome isn't composed of human cells, you can still argue it's a part of our functioning organism. It seems it would be nearly impossible to measure human digested calories vs bacteria digested calories, so maybe the results are close enough. Also, many beneficial bacteria release calories that we can consume, like butyric acid, which further complicates things.

[0] https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC5251283/

Let's consider a specific example: Lactose intolerance. The Wiki page for it is pretty good. So, despite the name, lactose intolerance refers to lacking the enzyme lactase, which is used to break down lactose. If you have lactase, then your human cells can use the calories from lactose; if you don't, then the bacteria get the lactose. Wiki says "Symptoms may include abdominal pain, bloating, diarrhea, gas, and nausea", which sounds like the bacteria do indeed eat it; if the bacteria couldn't extract calories from it either, then I assume it would just pass through and there would be no symptoms.

Thus, if Bob and Joe eat the exact same diet that has some milk products, and Bob is lactose intolerant while Joe isn't, then Bob's cells get fewer calories from that diet than Joe's. If Bob and Joe's bodies are otherwise identical and follow identical exercise routines, then I would assume that, like, if the diet is exactly enough to maintain Joe's weight, then Bob would lose weight; and if it's exactly enough to maintain Bob's weight, then Joe would gain weight. (Right? For sake of illustration, we could imagine that most of the diet's calories are from milk, and assume Bob can tolerate the nausea.) Yet "calories in" (measured as food entering stomach) are identical, and "calories out" (measured as CO2) might also be identical.

Lactose is a specific, well-understood example of some people absorbing nutrients much better than others. I think there are other examples, and I expect there's a lot of variation in absorption efficiency that's less known. When you hear about people who eat lots of food and remain thin, I suspect this is part of the explanation. And whether their bacteria get the calories instead, or whether it passes through untouched, might show up in CO2 measurements but I don't think it would be related to body fat accumulation.

In a conservation-of-energy sense, "calories in" certainly gives you an upper bound on how many observed "calories out" you can produce without losing weight. But I don't think there's a lower bound on how inefficient someone's digestive system can be (except "zero"), or a practical upper bound on how much their cells might burn energy without us noticing (without close observation). I think, if you wanted a complete accounting of calories-out that would actually match the input, you'd need to add up (a) the heat a person puts out (via contact with air and surfaces, also infrared emissions), (b) the work they do in a physics sense (e.g. lifting heavy objects), and (c) the amount of un-burned calories in their stool (or any other excreted substances).

> Lactose is a specific, well-understood example of some people absorbing nutrients much better than others. I think there are other examples, and I expect there's a lot of variation in absorption efficiency that's less known. When you hear about people who eat lots of food and remain thin, I suspect this is part of the explanation. And whether their bacteria get the calories instead, or whether it passes through untouched, might show up in CO2 measurements but I don't think it would be related to body fat accumulation.

Yeah, the blind assertions I have seen that people basically always absorb pretty much 100% of the calories of the food is weird. We already know that some forms of calories like fiber have very low absorption rate. The Atwater indirect system of calculating calories takes that into account, but is still just an estimation, since it uses average calorie values for protein, carbs, and fat.

And so I've just noted that calories on packaging is just an approximation. An individual food may actually have more above average proteins than below average, etc, which can skew the real calorie count. For example, nuts are known to have less calories than indicated on the label, with whole almonds having 20% fewer. (https://doi.org/10.1093/jn/138.9.1741S) This is also ignoring the fact that many foods, especially those prepared by people are not always super consistent in sizing. A subway sandwich prepared correctly should on average have the calories subway claims, but we all know that some locations will follow the correct procdure more closely than others. Etc.

The other issue with just blindly going with calorie counting (which is really on tracking calories in) is that the differences in the calories one takes in will cause changes in the calories one expends. Eating fairly substancially less than your body is used to will almost certainly cause one to feel bad, and avoid doing as much, meaning fewer calories out, at least partially offsetting the the calorie reduction. But people are generally not measuring the calories expended very closely, if they bother doing it at all.

> or a practical upper bound on how much their cells might burn energy without us noticing

Well, heat dissipation places a bound on that.

> At that point though are we kinda arguing semantics? While our microbiome isn't composed of human cells, you can still argue it's a part of our functioning organism.

It's not semantics, because when more calories are used up by bacteria they only sustain the amount of bacteria inside you, which then die and leave your body on a relatively quick timescale.

It's like if your fat cells could only store fat for a month before it gets discarded.

So it's important to know how much is each, if they can both vary.

What? No, I haven't gained weight, my bacteria is just getting a little heavy

>"oxidation done by bacteria that feast on calories your human cells didn't get"?

That would still be part of calories in.

> When most people think about exercise for weight loss, they imagine long exhausting sessions on the treadmill, dripping with sweat

This is a major education/communication issue. When I switched to weightlifting, I started seeing rapid and significant results. And I don't even really sweat from it (except on leg day)

> a terrible strategy

It may be less effective for losing weight, but exercise, including and especially cardio, is a great and essential strategy for other health reasons.

> You'll build muscle which will increase the resting metabolism

This is another myth. Even if you put on a serious amount of muscle, the change to your daily calorie burn is insignificantly increased in the larger scale of things.

Don’t to strength training to lose weight, so Strength training to get strong.

The change in metabolic rate is a homeostatic adaptation of the body due to increased energy expenditure due to exercise. You can measure it in a metabolic chamber, and 200-300 calories per day during rest time is not unusual for male athletes.

I don't know if I can accept that offhand because high levels of muscle atrophy is a human adapted trait specifically to save calories for the brain. If muscle maintenance costs were so insignificant why would we have adapted a trait to make us physically weaker?

This is anecdotal but the difference between what I can eat working on a farm with having lots of muscle mass and sitting around on a computer with that same muscle mass was not really significant. But the difference between sitting at a desk with a lot of muscle mass and sitting at a desk with noticeably less muscle mass is night and day in how much I have to eat. With small and inconsistent amounts of strength exercise to maintain a bit more muscle mass again, my caloric expenditure went back up, far beyond what is lost from the exercise itself.

Some very bold claims, would love some citations to give them more credibility.

HIIT workouts are great for cardiovascular fitness and melted the fat off of me that I gained from a sedentary lifestyle spanning the last 2-3 years for example.

Meh idk. Look at any long distance runners. They are skinny. Based on my own ancedotal evidence when I am running often I tend to be 20lbs less than when I don't.

You have a few correct points but are mostly spreading misinformation. Repeated exercise will only improve efficiency by a few percent at most, and then only for certain activities. For cycling, efficiency hardly improves at all. The calories shown on gym equipment are often nonsense but the latest generation of fitness trackers are reasonably accurate and can be worn 24/7.

You have to get into really long cardio sessions with no carbohydrate supplements before that has any significant catabolic effect. This is not a concern for casual athletes.

Strength training is great, but it should be combined with some form of cardio in a comprehensive fitness program.

> latest generation of fitness trackers are reasonably accurate and can be worn 24/7.

I've heard claims of 30% inaccuracy. Not sure if that applies to the absolute latest generation but I'd be happy to know if my understanding is outdated