The tl;dr is that ketosis is not exempt from the laws of physics.
It is undeniably true that calories in vs calories out is a driving factor, it is not however the only factor.
Your article shows how you think about diet/weight, and is not really reflective of any strong scientific understanding, and, in my opinion, needlessly disregards "… insulin! Starvation mode! Carbs! Zones! That study I saw written up in the New York Times!", when there is actually something here, or atleast potentially here that is also a driving force in weight.
edited for politeness/accuracy
If you genuinely believe that net calorie balance isn't the sole determinant of long term average mass, then I'd like to know what else it could be. Saying "oh it must be more complex than that!" isn't such an explanation.
For instance, to gain weight (muscle), bodybuilders will consume large amounts of carbohydrates (for a variety of reasons), but the most important is spiking insulin in the presence of protein to shuttle the protein to the muscles to begin building them after breaking them down.
Similarly, obese people should be cutting all carbs out b/c of the same insulin spike.
But there are other foods which are highly insuligenic. Whey protein, for instance, can spike insulin. MCT oil at high doses can. Heck, egg whites with no fat (no yolk) to balance it can spike insulin.
The point is that calories are, at best, an incomplete picture. At worst they are misleading and a distraction. I'm of the believe that net calories still matter, but only to the point that you actually know what you are doing and are eating the right macronutrients in the right ratios.
It's all you need to know to lose or gain weight.
> A big factor in weight loss and gain are hormones and calories don't say a thing about those.
It depends how we're drawing the boundary of the system being modelled. But if the boundary is a single human body, then net calorie balance is a forcing function. No hormonal configuration can alter the laws of physics. If you maintain a net deficit, you will shrink and, if you don't stop, you will eventually die from starvation.
It needn't be linear. Heck, I've lost so much fat in the past year that my base metabolism has actually dropped by a meaningful amount. But so long as I adjust my inputs, I can affect the outputs. I am my own controller.
EDIT--because I am too lazy to wait to post to daughter comment--
It is possible, for example, that if I eat a FOO, which has 100 calories, it will change effeciencies of systems in my body in tangental ways so as to cause it to burn 5% more calories than it would have if I didn't eat a FOO.
I could also eat a candyBAR which has 100 calories, that causes it to burn 5% less calories than if I didn't eat a candyBAR.
Thus, conclusively proving that "calories in" and ignoring the actual foods eaten is absurd.
For the same reason, I say "long term average mass". Weight is sufficiently noisy that I can be pinned to the mat on a silly debate-club technicality while the larger issue remains unaddressed.
When I say "net calorie balance" I'm not talking about subtracting the calories on the elliptical machine from the calories on the chocolate bar. That's an approximation, at best, because of the stunning complexities of the underlying system.
Actual net calorie balance is unobservable.
What you can observe is the outcome of net calorie balance, which is long term average body mass: aka whether you're getting fat or not.
You don't need to actually observe all the complexity of the underlying system. You need only observe the inputs and outputs. Are you getting fatter? Eat less, or change what you eat. Want to get bigger? Eat more, or change what you eat.
There's no need to build a blinkenlights dashboard of every variable of every bodily system. You just look at the scale or the mirror and change your behaviour.
[edited for larger reply to your edit]
The question is what do you change.
If I wake up one morning and decide I'm going to make a change and reduce my caloric intake. Instead of having my normal 1000 Cal eggs and and bacon, I decide to have a 500 Cal glass of sugar water.
By lunchtime I'm starving and I feel week so without thinking about it I consume an extra 600 Cal over what I normally would for lunch.
Furthermore, keto fans aren't arguing that ketosis violates the laws of physics. Of course in the end it's energy in vs energy out. But the core belief is that the body doesn't process all food equally.
They are arguing in essence that the calorie is an imperfect measure of energy available for extraction by the body. Eating what is labeled as 1000 Cal of food A may cause more weight gain that eating 1000 Cal of food B. They aren't saying that the body magically shunts energy into the ether as long as you don't eat carbs.
Consider a completely imaginary hypothetical. What if 1000 Cal of food A was processed 100% efficiently so that no waste left your body. And 1000 Cal of food B was processed such that 50% of it left your body as waste. Additionally consider that different combinations may affect the percentages. So that for whatever reason eating food A with food B, may decrease the efficiency with which food A is processed.
I'm not saying that the above scenario is in any way true, but if someone proposes that this is the case you can't say he is denying the laws of physics.
I don't have the exact link to hand; but please take it from me on face value that I have had "ketards" do just that. I realise that most of you are sensible people, but sometimes ... well, I guess every group has its share of people who make the rest look bad.
> Eating what is labeled as 1000 Cal of food A may cause more weight gain that eating 1000 Cal of food B.
Right, so we're arguing about labels. That's why I always use the term "net calorie balance". I'm not referring to the label on the tin (though that's a usable first-order approximation in many cases), I mean the actual physical-physiological outcome for the day.
 - http://www.fourmilab.ch/hackdiet/e4/rubberbag.html
Quite simply, you have to consider how a calorie takes the path to becoming a calorie in our system, imo.
The trick is, what I so far found out, to establish a set of meals that you can actually stick to for a longer time without feeling nauseous, while still maintaining calorie deficit. There are also issues like insulin reaction; so far I believe in this one, as hunger doesn't seem to feel as bad and doesn't disable my thinking since around the time I cut out sugars completely (I used to drink a lot of them). But accounting for all those things only helps you to stick with your diet.
So bottomline, I think that most of the other mechanisms people bring up are important not for weight loss per se, but for the ability to stick with a given diet for longer, while calorie deficit does it work.
FYI: I'm on keto for just over two months (with lot of cheating unfortunately - there were so many parties recently...) and have lost 10kg in that time.
Somewhere I have the bones of a super ginormo followup post to my original "fat and simple" one where I discuss causality itself in more depth (for example, I came up with 4 axes for categorising kinds of causality; I can only imagine that some long-dead philosopher has beaten me to it).
Lots of these debates actually resolve around definitions.
Anyhow, the other stuff I've written under the Systems heading may be of interest to you.
As for the causality things, I don't know about philosophers, but there is some good writing on the topic by Eliezer Yudkowsky, both the older texts and the new ones about causality, like . I found them very insightful.
Anyway, off to reading systems stuff ;).
 - http://wiki.lesswrong.com/wiki/Sequences
 - http://lesswrong.com/lw/ev3/causal_diagrams_and_causal_model...
Eat less --> weigh less
Eat more --> weigh more
None of your analysis in anyway shows, or even hints at the 'fact' that Eating more will necessarily make you weigh more. It is totally possible that someone can eat 3k calories a day, but no carbs, and this could have all types of effects; like a slight increase in body temperature due to a different rate of caloric burning, or maybe not everything is getting digested and he is shitting out 1.5k calories a day for some dietary reason you don't understand.
In the same way you cannot say "well logically, I put 5 gallons of gas in a car and went 25 miles, therefore there must be 1 gallon of gas left" without knowing specifics about an engine; you cannot do the same with humans, which you essentially are. Further, our bodies/engines are dynamic; and some of our internal systems are more or less effecient depending on a number of factors that you don't understand (for example, it is possible that eating certain types of calories have chemicals/enzymes related to them that cause other systems in the body to change effeciency). You have one side right:
If you want to lose weight you can be absolutely sure that by cutting down calories, below a certain threshold, you will lose weight.
The words "net calorie balance" are carefully chosen to encompass your objection (I have it filed under "Diet Debate Gotcha #3,947: Thermogenic Effect of Food").
> But, then you go too far and say this is the only thing at play.
I do and I don't. What I say is that it's all you really need to know in order to control your weight. It's also, in the strictest narrowly-drawn causality, the completely explanatory mechanism of weight control.
I'm not arguing that folk on ketogenic diets lose weight. I'm not arguing that there's no such thing as ketogenesis. I'm just saying that in the long run, the direct, immediate cause (such as it is) is one of net calorie balance modulo noisy oddities like water retention.
This is bad.
See my other comment on hormones. They play a HUGE role and not understanding them leads to statements like "it's all about the calories" or "I'm only eating 1000 calories" etc etc.
It can be, sure. Tooth decay, vitamin deficiency, muscle and bone wasting, all that jazz.
But are we still talking about weight control or not? Because people love to make it super ultra complex when the basic control mechanism is fairly straightforward.
My hyper-elaborate advice for the more general "health control" case (as opposed to "weight control") is:
1. Eat more to gain weight, less to lose weight, and about the same to stay about the same.
2. Make sure you get plenty of protein. It's good for you.
3. Eat a variety of foods.
4. Lift weights.
5. Do something that makes your heart pump really hard for a while.
I mean for myself I have zillions of tweaks. But it's easy to go off the deep end chasing that 1-2% optimisation when all most people want is the 20% of information that gives 80% of the result.
Perhaps its context... I don't see things, where I am, as simple as you write them above.
Perhaps I'll fire up my daily burn account again and get to it. Part of the fun of this was that I have been able to eat when I felt I needed it and not worry about counting...
HOW much more? (HOW much less.)
Lizzie Velasquez trivially demonstrates the inadequacy of your observations.
This doesn't mean that weather forecasting, economics, agile software methodologies -- to pick just a few famous examples of subjects dealing with complex systems -- are totally broken tools that must henceforth be discarded.
It just means that we have to pick our battles.
Controlling systems by incremental adjustments works perfectly well. In fact it works for highly predictable simple systems too -- you can take variables like shell mass, powder load, wind velocity, humidity and predict with enormous accuracy where an anti-aircraft shell will go when fired.
Or you can use tracer bullets.
(Yes, this is the elegant little example from The Pragmatic Programmer).
Not that I want to ridicule you here, but it is interesting that two of your three examples fucked up so bad at various times we WOULD be better off if we discarded them (or even better: Send them back to research until they provide reliable results) - economics and weather forecasting. For the third one the bets are still open.
For the general case/dieting: The observation that a net calorie deficit always leads to weight loss seems correct. The observation that you can always induce such a deficit is also correct. Using this knowledge to state "eat less, you will lose weight" leads to what I call the "dumb and proven way" - It will work(1), but your body will(2) fight you tooth and nail at every step, i.e. your body will do everything to reduce the net deficit. The open question: Is there a way to get a comparable/bigger net deficit without fighting your body? Keto, paleo and whatever try to provide an answer. For me, they fall into the agile software methodologies category: There may be benefits. Or not.
(1) It will work if you can stay with it, which is unrealistic for many cases, but people still like the "idea".
(2) Some bodies fight hard, some not. That's life.
Doesn't matter. Just keep loosing / gaining until you reach the desired weight and then adjust to stabilize. It will take different time for different people and/or food combination, but in principle, you can just adjust the amounts and you'll get there.