> To lose weight, you simply need to intake fewer calories than you burn.

While this is true, there a lot more complications.

You body has its own idea of your weight set-point, and tries to keep your body mass in that range. Any short-term intake / expenditure imbalance will be corrected when sufficient calories are available afterwards.

If you are suffering a longer-term shortfall of calories, your body will "turn down the thermostat" in a couple ways. One by literally producing less heat, but your metabolism slows down in other ways, and an emphasis is put upon storing calories as fat.

So if you cut your calorie consumption, and your body decides to cut calorie expenditure even more, you can gain weight.

Also, your body will reduce muscle mass in a reduced caloric intake situation, because it will burn that muscle mass as energy to power the rest of your body, and also because muscle mass just uses more energy even when it is not doing anything.

Going on a diet that causes you to lose muscle mass is a recipe for rapid weight gain after you stop dieting.

Unfortunately, many fad diets will work in the sort term, but will make it easier to gain weight back later on.

So, in other words, that means that, even if "calories in, calories out" might be trivially true, which I would still imagine it is because thermodynamics, it's not actually useful as weight loss advice?

Because the human body is not a passive system. It has all sorts of autonomic processes designed to control both calories in and calories out, and they have a tendency to subvert and/or counteract anything you're consciously doing to adjust your overall energy intake and expenditure.

I'm obviously no health scientist, but, just thinking out loud, that seems pretty believable? Partially because, of course, nothing's ever that simple. But also, speaking purely speculatively, I can't imagine my body responds to me consuming a 1,500 calorie holiday meal by immediately producing three more pounds of fat tissue, and then making it disappear the very next day. So, even from that, it seems implausible that the body's arsenal of ways to deal with simple day-to-day and hour-to-hour variation in energy consumption has to go way beyond simply growing and consuming new tissue. Which is what it would seem to imply if useful weight loss advice really could be as simple as "calories in, calories out."

Elsewhere I linked an article on the variability of the brain's calorie consumption, and one of the sources it cited was a table of calorie expenditure per hour across several activity types. Including things like reading a book or preparing a meal. It wasn't nearly detailed enough to know for sure, but, based on what I saw from a cursory glance, it seemed at least plausible that your body could completely counteract several hundred calories' worth of reduced food consumption by, say, simply making you unconsciously be a little bit less fidgety throughout the day.

I would still suggest that "calories in, calories out" is still solid weight loss advice. There are two major confounding issues that might make it appear incorrect. The first is that out is variable, and the second is that some parts of the system are noisy. The solution to both is to try to measure accurately and frequently. The best things one can do to achieve this are daily weigh-ins at approximately the same time and trying to account for the bulk of one's caloric and macronutrient intake.

Is it, though? To me, part of what qualifies advice as solid is that it has to help people who take it achieve the desired outcome. My understanding is that there's a staggering lack of evidence that that is the case. And not for lack of people looking for it.

Which leaves me thinking that this is an idea whose memetic fitness far exceeds its practical value.

The elephant in the room here is the article itself. The basic premise here is that internal bodily processes can increase your energy expenditure by as much as several thousand calories over the course of the day, even when you're being physically sedentary. And if it can autonomically increase the burn rate, surely it can also autonomically decrease it.

I've certainly noticed that I have a more difficult time thinking clearly on days when I'm not eating as much as usual. I wouldn't be surprised if a similar thing happens if I take a long bike ride without eating any extra food. Though this isn't something I've paid attention to in the past, so I suppose I don't really know. But still, if the body increases calorie expenditure during periods of higher brain activity, then it is certainly just as capable of reducing brain activity in response to a reduction in readily available energy.

I certainly can't speak for you, but it has worked quite well for me as I described it, for both gaining and losing weight as needed. I sympathize with people who do a poor job of measuring, either through inconsistency or incorrect calculation, but we don't blame the game of chess for people who play it poorly or suggest that they are evidence that it does not provide value to those who do, do we?

I can't speak for you, either. But I'm not talking about individuals' stories here. That's one of those, "the plural of anecdotes is not data," situations. When it comes down to empirical data, it seems to be a bit like the situation with acupuncture: it works just well enough to ensure that there's always someone who will show up and say, "It worked for me!" when the subject of its poor performance in clinical trials comes up, but not well enough to demonstrate practical efficacy under scientific scrutiny.

Perhaps that really is because basically nobody is assiduous enough about their calorie counting to make it work. But, even if we take that as true for the sake of argument, insofar as the point I'm making is, "This advice has a terrible track record of helping people lose weight," it doesn't work as a counter-argument. Quite the opposite. It works as a supporting argument, by showing one possible reason for why it has such a terrible track record.

I also don't think that it has legs as an idea for how best to reduce the obesity rate. If it were really that easy, then you would expect the population's average BMI to be much higher back when people didn't have the means to effectively calorie count, and it would steadily go down as the means to calorie count more accurately become more widely available. Instead we see that the opposite is true.

Absolutely. I was weighting before and after sleep every day, and results had fluctuations up to .5 kg, but after two weeks the trend was easily visible.

Just as a general comment: weight alone is a shit measurement for overall health. You really want to know your body fat percentage, at a minimum.

I'm curious if you have a simple, accurate way to measure body fat percentage at home. If you do, would you please share it with the rest of the world? It's probably worth quite a bit.

This study says that women feel hunger more strongly than men due to physical differences in the brain. True or not, the idea that some people just feel more hunger for the same amount of calorie deficit could explain a lot.

Also, "calories in, calories out" is the second thought-terminating cliche[1] I've encountered today!

[0] https://www.bnl.gov/newsroom/news.php?a=110876 [1] https://en.wikipedia.org/wiki/Thought-terminating_clich%C3%A...

One self-regulating thing really does exist. If you are already overweight, the body can self-regulate itself, by extracting fewer calories from processing from eaten food. You can take in food for 3000kcal, but the already overweight body can take in just 2700.

This has only one effect: when a person decides to lose weight, it'll make it harder for him, because eating slightly less than will have no effect at all, and the body is already used to eating a lot, so reduction in incoming food brings immediate discomfort.

But the opposite direction is rock solid: if you don't eat enough to compensate your passive calorie burn, you will not gain weight ever.

Anyway, this method helped me to go from 96 kg to 83 kg in 10 weeks, taking on average 1750..1900 kcal per day. For me it turned out pretty easy. First two weeks were the hardest, and I took in up to 2000 kcal, gradually bringing it lower.

> You body has its own idea of your weight set-point, and tries to keep your body mass in that range.

There's not much scientific evidence for "set point weight" or "starvation mode" or other similar concepts. People regain weight after dieting most likely because they go back to their old eating habits rather than making a lasting diet changes. But it's more convenient to blame their body stubbornness than their own lack of discipline.

Is there data to back up an individual 'set-point'? People think differently, so I can only speak to myself:

If I was heavier than desired, and I noticed my body was gaining weight while I am suppressing caloric intake, I would reduce intake even further. Call the bluff.

Of course, easier said than done. It's perhaps a masochistic mindset, forcing yourself to feel hunger, and obstinately refusing to give in. Since I was young, my conscious response to hunger seems different than many. I can easily ignore it for hours, if I am focused on something interesting. Hunger is an annoyance I typically ignore. The body screams "Wahh, I'm hungry! I'm going to make you feel bad until I eat!" and my internal voice says "Go right ahead. Suck it up, you're fine. I'm having too much fun to tend to you. Maybe you get something in a few hours."

If anything, I probably don't eat 'enough'. But I don't try to eat less. I eat whatever I want whenever I want. I am very happy with my weight. I eat a wide variety of nutritious food. But ultimately it's just annoying that we have to eat at all.

Basically what you allude to is the metabolic rate. Your body has a metabolic rate, and if for whatever reason this gets out of whack - eating unhealthy, gaining a lot of weight, it becomes very hard to come back to baseline. Hence the yo-you effect of most diets.

I find exercise sets the tone for what and how much I eat. After a week of working out every day, I feel better and have more energy for eating well. Eating well, in turn, makes me feel even better, and I'm able to keep the whole thing going for longer. In the end, it's a game of willpower and finding what helps you maintain your willpower.

Not to mention, lifting weights increases strength and adds muscle.

> I find exercise sets the tone for what and how much I eat

I agree. I can lose weight simply by restricting calories, but exercise is what makes restricting calories doable. I get far more from the exercise than just whatever few calories it burns.

Agree, it's hard to eat badly when you are putting in the time to work out, that's the case for me at least. But I also hear from people that they decided to eat badly, because they had an intense work out, and feel it's ok to indulge.

> Exercising is almost irrelevant

I get where this is coming from, but I really feel like everyone has over-corrected on this and ended up being wrong again in the opposite direction. Exercise burns a significant number of calories. An hour run can easily burn 700 calories for someone my size (~70kg). Running an hour a day 6 days a week burns more than one pound of fat a week. I run less than that amount and my phone estimates I burned 15,000 calories last month from running. That's not a get-slim-quick magic pill, but that's really significant!

Exercising for 20 minutes once or twice a week is pretty negligible and people over-correct by eating more. But a consistent, easily-doable exercise habit is a huge source of additional "calories out".

> An hour run can easily burn 700 calories for someone my size (~70kg).

If you can run for 1h then you are quite likely already in a good shape (if not, running 1h every day would kill your joints).

> Running an hour a day 6 days a week burns more than one pound of fat a week.

Usual advise is to run at most every other day to let the body regenerate. That said, eating 500kcal less each day has the same effect and is much easier then running 1h six days in a row.

Exercise and calorie reduction don't have the same effect. Running stresses the body which promotes muscle growth and reduces resting heart rate (among lots of other physical benefits). Calorie restriction forces to body to fill an energy deficit, usually by burning fat but potentially also muscle mass.

But running (compared to sprinting or weight exercises) is not exactly good at building up muscles.

Running (in GP's case) or exercising in general has the added benefit of building (up to a point) more muscle. More muscle mass means higher basal metabolic rate. Higher BMR means you burn more calories all the time.

So yes, a 500 kcal deficit every day (without adding exercise) is comparable in the short term to the runner burning 700 kcal extra 5 days a week (but not adjusting their diet). But, especially if that muscle mass is sustained, the runner or person engaging in regular exercise is going to be better off in the long term with respect to keeping the weight off.

Exercising does only one thing for weight loss: it builds up your muscle mass. Muscles have higher 'passive' calorie burn than fat tissue. Thus, you can take in more calories without adding weight, and if you eat the same as before adding muscles, you'll lose weight faster.

Why do you say that? I mean, I just pointed out it burns me 15000 calories a month and frankly I haven't built any muscle from running.

I read a paper recently that showed we tend to offset exercise with lethargy elsewhere without even being conscious of it. Anecdotally this seems true as I'm currently sat on the sofa following a thirty mile bike ride this morning.

Completely agree.

However exercise is essential for your mental and physical health so you must keep doing it.

I found a weird side effect though. I lost a lot of weight. Then didn’t find exercise difficult and quite enjoyed it. Now I do a lot of exercise because it’s fun and eat more than I did originally. Reprogramming myself has been an interesting experience.

While it is true that exercise itself does not make you spend much energy, doesn't strength training build additional muscle which in turn makes you need more energy to maintain that muscle, so you increase your basal metabolic rate? Sounds like it'd be more effective for losing weight than cardio on principle.

You are correct. It's just that gaining an appreciable amount of muscle takes a long time. So for it to have any impact would take a couple years of growth

These kind of posts attract lots of debate, maybe less so on HN, but to strengthen OP's statement: every technique beyond total calories intake is an optimization. Sometimes, if your body and lifestyle is in a situation that has many opportunities for non-calorie weight loss optimization, it may seem like total calories is not the most important factor. This is a confusing illusion because those optimization opportunities will change over time, and as you address them. Total calorie intake is the underlying reality of weight loss that will not change.

That said, there are a lot of useful optimizations and hacks out there. OP says exercise is almost irrelevant, but I can say that training up the ability for endurance exercise is really effective for me personally. During quarantine I've gone from sedentary to completing 10 mile runs, which have noticeably helped me lose fat. In the past I've also had successful experiments with restrictive diets like paleo, keto, and intermittent fasting. YMMV; experiment with optimizations, but never forget about total calories.

My experience of losing >150lbs agrees with this statement. Ruthless, excuseless calorie counting was the only way to lose weight, and by far the hardest part was summoning the will to not eat more. There are strategies for hacking that last part, but it seems to be incredibly subjective as to what works for any given individual.

Got any pointers you'd be willing to share? I need to lose a similar amount. I don't want to have a heart attack in my 30's or 40's. The existential dread and a strong hatred of my behavior have done horrible things to my psyche...

AnIdiotOnTheNet said a lot of what I'd say, but one thing I'd add is: to lose the ~90 lbs that I did, I had to realize that I would just be hungry for a long time. If I had listened to my normal hunger impulses, I would have kept all of that weight on or gained more, so it meant I had to get really comfortable just being hungry. A lot of meals left me unsatisfied, but eventually your stomach adjusts to the quantity of food you start eating. That doesn't mean, however I didn't get hungry throughout the day. Drinking lots of water and coffee helped in this regard; when it was especially bad, I was drinking a lot more water to keep my mouth busy

One last thing I'll add is that impulse control is 1000x easier with good sleep and the weight seem to come off a little faster when I was well rested

Pointers.

1. Install fatsecret (note that it does overestimate your passive calorie burn, it calculated 2500 for me, but in fact it was closer to 2200). If you can't pick the exact product you ate, pick the one with the hightest calorie count. In this case, overestimating works in your favour.

2. Start slowly. Do not start right away with 1500 calories/day, stay near your net zero point for a few days, or a bit lower

3. Then try a bit lower. Lower more, if you can. Repeat every few days.

4. Always pedantically calculate all calories. Kitchen scales are a must for any nonpackaged food with known weight.

Often the thought of the necessity to fill in weight and product removes the desire to devour something

5. Respect yourself! DO NOT eat something that you badly want to eat because you are a person who is controlled by his mind, not his desires! YOU are in charge, not your hunger

6. If you BARELY, BADLY need to eat that chocolate, eat it. But not 100g, but 1/8 of it, like 12,5g. AND count it.

7. Try to sleep more. When you sleep, you can't eat.

8. Buckwheat rules, simple to cook and has every mineral you need to stay healthy. On some days i got by by eating 250g of buckwheat and 150g chicken.

That's it, do it diligently and your weight will go away SOON.

I ate everything, from cured pork fat to chocolat, at any time, not caring for it at all. After 6, noon, midnight, just stayed below the threshold.

Good luck. :)

Like I said, the simple truth is that you must count your calories, with no cheating or excuses. There are several difficult parts in the implementation:

Your brain doesn't want you to count calories, nor does the food industry. Your ability to estimate calories is not likely to be very good. I mitigated this by eating almost exclusively pre-packaged and labeled food and intentionally overestimating any time I deviated.

Your energy level will suffer, at least at first. You kinda just have to push through this, but caffeine (or other stimulants) can make it a bit easier.

It's hard to stay motivated. I found an athletic activity I enjoyed, which provided motivation because bodyweight was a significant limiting factor. It also burns some calories, which helps absorb the blow of any underestimation. Do not allow yourself to count these negative calories in your total, it's just an excuse your brain uses to try and get you to eat more. I also weighed myself every day to ensure I was moving in the right direction, but be careful because water weight can make it seem like you gained or lost a few pounds day-to-day.

Oh yeah, your brain will try and trick you into eating more. I can't tell you the number of times I'd somehow managed to convince myself I hadn't actually eaten lunch yet or only had one serving of something. Be on the look out for this.

For some reason, the people around you won't like that you're losing weight. It's weird. They'll encourage you to eat more if you go out to eat with them, they'll re-offer you food even after you've already turned it down, they'll try and get you to skip exercise, they might even tell you that you look sick and unhealthy. Unless they're a doctor, ignore them. Actually, even if they are a doctor take it with a grain of salt.

When you fuck up, just accept it and move on. If it is a small amount of excess you can make it up by cutting a little harder for a few days after, but if it is big it's best to just pretend it never happened.

Once you reach your goal weight the hardest part starts. You have to start bringing your eating habits back to something kinda like normal so you can maintain them forever. You will, unfortunately, never be done. Trust me, the second you let yourself believe you can eat like a regular human being again you'll put on 30lbs and have to work that much harder to get it off. No one you know who hasn't lost a bunch of weight will understand.

> Once you reach your goal weight the hardest part starts.

For me it is not that hard. I just allow myself some leniency during the periods when there are many upcoming parties/birthdays/etc and can put in 2-3 kilos. Then I pick a period when there are no such events planned and go to calorie counting routine.

Of course, I maintain weighting routine all the time, every day.

> Trust me, the second you let yourself believe you can eat like a regular human being again you'll put on 30lbs and have to work that much harder to get it off.

I remember my doctor mentioning that. Having been seriously obese will permanently affect your metabolism. You'll burn less calories than you normally would having never been overweight.

As far as athletic activity goes, I started playing airsoft after getting vaccinated because my friends are into it as well.

It's worse than that. The body doesn't like to lose supplies, so any calories burnt by exercise will be reclaimed by the body, which means that in any case (exercise or not) you'll need to eat less than what your body asks of you.

For some people this is cancelled by the virtuous side-effects of exercising, most notably sleep quality and low stress levels, as sleep and stress are the two most important levers on hunger/self-indulgence. For some others this is compounded by a conscious decision to allow oneself to eat sizable portions (or snack) to make for the effort, which immediatly cancels the calories deficit induced by exercice, most probably with compensation, considering how few calories are burnt by standard exercise durations.

Right, exercise is good for your heart and bones but bad for weight loss if that is your goal. Also, weight loss is about stress and emotions. I've seen lots of people have desert at lunch because "I'll work out later" but then they bail on that too. Additionally, a lot of people feel famished post workout and tend to overeat even consuming more extra calories than they burned during their exercise session. There is also the time element. It takes 0 minutes to not eat 500 calories a day.

It is a LOT more complicated than that, and your last sentence has one of the largest clues

Timing of eating relative to your daily metabolism, as well as utilizing (or not) different metabolic modes has a LOT to do with how food energy is stored vs burned vs dumped.

E.g., Intermittent Fasting is starting to be recognized as a highly useful method for weight and health control. At a high (oversimilified) level, consider that your body has two modes, storing energy vs removing energy from storage for burning. Intake of food more or less constantly (vs only at limited times) keeps the body in storage mode. OTOH constraining eating to limited periods during the day forces the blood sugar down and causes the body to switch to taking energy from storage. Thus, people can intake the same calories and do the same exercise/exertion levels, yet lose more weight when they restrict their calories to within a 8-12 hour period during the day.

Similarly, studies with holding amounts of food and exercise constant, but having Group A do their running before breakfast, vs Group B running the same amount sometime during the day resulted in greater weightloss for GroupA - they were forcing their body to dig deeper into their stored energy instead of just burning off of the circulating blood sugars from the current meal, because of the longer fast before the run.

And this is only one of the many factors that affects how storage works.

So, sure technically, it is 'intake fewer than burning', but that is a triviality considering all the other metabolic factors that can affect. So, good job cutting out those midnight snacks! (I've found that moving the last bite to before 4PM on several days a week makes a big difference, but YMMV)

There is always the Sir Ranulph Fiennes weight loss diet:

"I went from 15½ stone to nine at the halfway point, despite eating 5,000 calories a day!"

That's 91 pounds - with just one easy trick involving Antarctica:

https://www.buzzmag.co.uk/sir-ranulph-fiennes-interview/

Probably, calories are burned to compensate for the heat lost due to extreme cold. Never tried counting calories in Antarctica, so it's just a guess.

Losing 12.5kg without exercise would leave you quite weak and likely in a “skinny fat” state.

Aerobics is indeed not a good way to lose weight and yes you can’t outrun a bad diet but simply eating less isn’t a good solution because you end up with a low metabolic rate at the tail end of it and you’ll gain that rather quickly.

Weight training with eating at or just above sustenance for your target weight (as long as it’s now below 10-15% of your current rate) is really the best way to go.

You end up building muscle which maintains or even increases your metabolism and unless you starve yourself (or you had an extremely high muscle mass to being with) you’ll maintain and likely even increase your muscle mass even with an effective caloric deficit.

You won’t come out as a body builder out of this regiment, but you’ll lose weight and or do a body transformation over a course of 3-6 months depending on how much weight you actually want to lose.

That said it doesn’t work that well if you are obese and in terrible shape at that point diet + low intensity mobility exercise is needed until you can get into a shape that would allow you to do weight training without injuring yourself.

I do agree that the time of your meals isn’t that critical yes it has an effect but most people aren’t in a spot when they need to min max everything, macros, fasting, and other shenanigans can make a difference and when stacked correctly a big one but they also require even bigger investment and self control.

Find the minimal effort routine that would prevent you from turning into the humans from WAL-E and stick with it, it’s far easier to do something for 1-2 months longer if it’s less demanding than put in a lot of effort to try to get there a little bit faster.

Beyond that just maintain a reasonable level of strength to defer the effects of aging. If you are a male and you can’t bench your body weight in your mid 30’s or do pull ups you are weak.

This story is simplistic and doesn't represent the dynamic nature of the human body and mind. For example, as you reduce your calorie intake, your metabolism also slows down. This means you have to exert more willpower to consume the same amount of calories below deficit than you used to. Exercising is absolutely vital in establishing long term habits for losing weight and just being healthier in general.

But your basal bodily need (aka basal metabolic rate) does not really drop, as its bulk does not involve active digestive functions, but primarily circulatory processes, respiration, keeping your body's temperature up and so on - all the things that are non-negotiable to keep the body alive around the clock.

The number varies slightly with genetics and age, but does not vary notably between fasting and eating, nor between sedentary and active lifestyle, and averages at about 26 kcal per kilo body weight. This parameter is what makes up the resonable daily intake limit to aim at (or under) to let the body consume itself through catabolism (ideally lipolysis) in the safest way possible, without having to involve exercise.

Its more than just calories. What your body does to those calories matter too. Your body's chemistries matter.

You're absolutely right about exercising helping lose weight. An hour on a bike is 500-600 calories. A lb of fat is ~6000-8000 calories.

as a single example, I lost 35 lbs (16 kg) eating 4000-4500 calories a day (no carbs). I exercised 1 day a week playing ultimate frisbee in a local rec league.

> A lb of fat is ~6000-8000 calories.

A lb of fat is always 3,500 calories.

Edit: Thanks to abfan1127 for pointing out my age. 4,100 it is!

and I wouldn't say always:

"Pure fat has a very high energy content, or about 9 calories per gram. This amounts to about 4,100 calories per pound of pure fat.

However, body fat is not just pure fat. Body fat consists of fat cells, called adipocytes, which also contain some fluids and proteins in addition to fat.

Therefore, the calorie content of body fat is going to be a bit less than the calorie content of pure fat."

[1] https://www.healthline.com/nutrition/calories-in-a-pound-of-...

Not on the moon! Seriously though, I couldn't remember its exact value.

Great point! One lb on Earth is .17 lbs on the Moon, which leads to 5.9 * 4,100 = 24,118 calories per lb of fat on the Moon's surface.

You only need to eat less Calories, you don't necessarily need to eat less food.

Filling your stomach with the right foods can leave you feeling full while still losing weight.

Foods packed with fibre, mainly.

Which, surprise surprise, are mostly vegetables, beans, nuts, and whole grains.

Everybody knows those foods are healthy and will keep you trim, but hardly anybody eats them exclusively.

Hardly anybody eats vegetables? This is the first I’ve heard of it. Did you know some people only eat vegetables?

I added "exclusively" to clarify.

I am vegan, so yes I do understand that some people only eat vegetables. But there's not many of us!

Half of this comment is wrong:

It's not a matter of "simply" taking in fewer calories. Your body has a weight setpoint that it likes to maintain, and if you just decrease your caloric intake while eating the same type of food at the same intervals, your body will start burning less. "So just eat less, count calories and weight the food using kitchen scales." is equally wrong in the same way.

There have been scientific studies done on this (from "The Obesity Code", which is a good book backed up by a lot of empirical evidence (some notes are at http://www.criticalthink.info/webindex/BkObesityCodeFung.htm)):

> Thirty-six young, healthy, normal men were selected with an average height of five foot ten inches (1.78 meters) and an average weight of 153 pounds (69.3 kilograms). For the first three months, subjects received a standard diet of 3200 calories per day. Over the next six months of semi-starvation, only 1570 calories were given to them. However, caloric intake was continually adjusted to reach a target total weight loss of 24 percent (compared to baseline), averaging 2.5 pounds (1.1 kilograms) per week. Some men eventually received less than 1000 calories per day. The foods given were high in carbohydrates, similar to those available in war-torn Europe at the time--potatoes, turnips, bread and macaroni. Meat and dairy products were rarely given. In addition, they walked 22 miles per week as exercise. Following this caloric reduction plan, their calories were gradually increased over three months of rehabilitation. Expected caloric expenditure was 3009 calories per day.

> [...] The men experienced profound physical and psychological changes. Among the most consistent findings was the constant feeling of cold experienced by the participants. As one explained, "I'm cold. In July I walk downtown on a sunny day with a shirt and sweater to keep me warm. At night my well fed room mate, who isn't in the experiment, sleeps on top of his sheets but I crawl under two blankets."

> Resting metabolic rate dropped by 40 percent.

> Interestingly, this phenomenon is very similar to that of the previous study, which showed a drop of 30 percent. Measurement of the subjects' strength showed a 21 percent decrease. Heart rate slowed considerably, from an average of fifty-five beats per minute to only thirty-five. Heart stroke volume decreased by 20 percent. Body temperature dropped to an average of 95.8°F. Physical endurance dropped by half. Blood pressure dropped. Men became extremely tired and dizzy. They lost hair and their nails grew brittle.

> Psychologically, there were equally devastating effects. The men experienced a complete lack of interest in everything except for food, which became an object of intense fascination to them. Some hoarded cookbooks and utensils. They were plagued with constant, unyielding hunger. Some were unable to concentrate, and several withdrew from their university studies. There were several cases of frankly neurotic behavior.

Let me repeat a fragment of that from above: Resting metabolic rate dropped by 40 percent. If you just try to "overpower yourself to eat less", you will temporarily lose weight, but eventually you'll give in, and then your weight will return to a higher level than before - something that is also supported by scientific studies.

> It is absolutely irrelevant when to eat: only the amount of calories intake matters.

This is also false - eating continuously during the day leads to insulin resistance and weight gain, while eating the same amount of food in a smaller region, while not necessarily health, does not cause that effect.

I don't agree. If you starve yourself very fast, the body starts to shut down, and of course your passive burnrate decreases significantly. It is like keeping only the most critical systems powered when you lose your main power generator. (See Apollo 13 movie for visual representation).

Still, this happens when you starve. If you do it gradually, the body adjusts. The main thing is to keep in mind that person can survive just fine on 1700 kcals, and that you are not dying when hungry, it's only a discomfort.

I don't think the metabolic impact of a starvation diet (only getting less than 1000 kcal while expending 3009 kcal, that's a 2000kcal difference!) can be compared with a normal weight loss diet, e.g. net negative of ~500kcal.

So what should you do?

Get as many of your calories from fats and protein, and as little from carbohydrates, as you can (as the former cause you to feel significantly more satiated (naturally leading to less eating without more hunger) and the latter cause spikes in your blood-sugar and insulin).

Eat in a narrow time window (to encourage ketosis), infrequently (to avoid insulin resistance), not too late (because eating late is associated with weight gain [1][2]), as consistently as you can (your body can adapt to eating only once a day, resulting in you not being hungry at other times - mine has).

Exercise (because getting a minimum amount of exercise will stimulate weight loss and is really important for physical health in general beyond just weight loss), but don't worry when you get hungrier as a result, or try to maintain your previous eating quantity - eat until you feel full.

Get enough sleep, because sleep deprivation causes you to feel hungrier[3].

One of the underlying patterns in the above is the focus on controlling hunger, instead of directly trying to control CICO. If you just try to naively generate a caloric deficit through sheer force of will (same meal composition and timing, just decreased volume), your body will respond by increasing appetite levels, which is one of the reasons why the majority of those who lose weight gain it back again afterward. If you can affect your appetite, however, not only is sustained weight loss possible, but often automatic.

[1] 0064 of https://sleepmeeting.org/wp-content/uploads/2018/10/abstract...

[2] Yes, I should have provided more sources here - The Obesity Code cites a lot of studies, but I can't find the citations online.

[3] https://www.medscape.com/viewarticle/533105

"Exercising is almost irrelevant,"

But still crucial. It has several other advantages.

It can't be almost irrelevant and crucial, that is nonsensical.

It is irrelevant because your appetite will also go up. Nobody talks about other advantages on well being, only about your weight.

"Nobody talks about other advantages on well being, only about your weight."

It is well established and recognized that not only does exercise improve brain health, it reduces the likelihood of several illnesses including many kinds of cancer.

If a person talks about nothing statistically speaking except weight they are either clueless or using "weight reduction" as an umbrella term for life style changes that improve the general wellbeing and may or may not reduce weight as well.

Obesity is certainly statistically very much correlated with several illnesses but if we are concerned with general wellbeing it is not the full story.

Exercise is crucial to health, but not to weight loss.

Totally wrong. Not all calories are the same. And some chemicals promote hunger, take for example THC.

Exercise do seem irrelevant for this.

Calories are calories is much more true than people give it credit for. Here's a guy who ate nothing but twinkies and not only lost weight, but had all his health metrics improve: http://www.cnn.com/2010/HEALTH/11/08/twinkie.diet.professor/...

Human biodiversity is also much greater than most people give it credit for, and because of that, the fact that this one guy ate an all-Twinkie diet and became healthier is almost irrelevant - it's not even anecdata, because that would imply n>1.