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Liron comments on How I Lost 100 Pounds Using TDT - Less Wrong
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After listening to Gary Taubes' Why We Get Fat, I'm curious to know three things about your weight-loss diet:
Did you eat more or fewer grams of carbohydrates per day?
Did you eat more or fewer grams of fat per day?
Did you eat more or fewer grams of protein per day?
I cut certain deserts out entirely, which effectively I am sure means I reduced protein intake less than the other two, but I reduced all three dramatically.
Gary Taubes basically says that one generally loses weight if and only if one eats fewer carbs, so this is some evidence for his claim (not strong evidence, since it's consistent with most other models of weight loss too).
I would consider my experience zero evidence for or against Gary Taubes' claim, since every model of weight loss predicts that anyone successfully doing what I did would lose weight. Sounds like a very strong claim, but the word "generally" is murky.
Um... Is that logical? If you eat 3000 calories a day of fat and protein, wouldn't you still gain weight?
Why would I? The only thing thermodynamics tells us is that calories place an upper bound on how much weight a person can maintain/gain. The actual amount of weight gained/lost depends on the operation of regulatory mechanisms.
I am not sure I am convinced by this argument, for the following reasons:
If you think of calorie content / thermodynamics as an upper bound on how much energy can be extracted from the food, you have to make an argument for what happens to the unused energy. Even if you are in a biochemical state where not all the energy is used, there is still energy floating around in your body in the form of carbohydrates, fat and protein. I can think of three possible mechanisms for what happens to this extra energy, and I am not convinced by any of them:
(1) Calories are excreted unused in their original form. However, I don't think this happens to a meaningful extent
(2) If there is excess fat, nutrients are broken down to molecular constituents in a less efficient mechanism of cellular metabolism, ie, producing less ATP. This is a little more plausible than 1, but I think it would be evolutionary maladaptive to reduce the fuel efficiency of your engine unless it was absolutely necessary. Note that there are cases when the body does reduce the fuel efficiency (such as anaerobic metabolism), but I can't see how this applies here
(3) (Added): If there is excess fat, the body begins to run processes that are not strictly necessary, thus using more fuel. However, I am not sure what these processes would be, or why they would be triggered by fat and not carbohydrates.
I find it plausible that increasing fat intake will help you lose weight due to regulatory pathways such as insulin, but I think this pathway operates almost exclusively through changes in appetite. I fail to see any arguments why we cannot use thermodynamics (calorie input/output) as a very good approximation of predicted weight change.
EDIT: This comment is being downvoted. I am happy to delete it if it doesn't add to the discussion, but it would help me immensely if someone could explain why my reasoning is wrong...
EDIT2: I am not sure if I misunderstand the karma system, but I don't think you are supposed to downvote someone for disagreeing with their conclusions. It is possible that I am wrong in my conclusions, but I don't think this in itself is reason for downvoting.
If you disagree with my arguments, you can dissect them in the comments. Reasonable arguments with incorrect conclusions are still valuable in a discussion, and if you show why they are wrong, you will not only help me update my priors, but also help reveal a flaw in how non-trolls come to their beliefs. Hiding the comment prevents this. I don't see any reason for downvoting, and I think the downvoters need to ask themselves if they are downvoting due to mood affiliation / cognitive bias.
(4) Calories are excreted unused not in their original form.
What do you think shit is made of? When dried out, it will burn -- that's calorific value right there. Everyone takes in more calories than they turn into heat and motion.
(5) Thermogenesis. If that's impaired, you won't burn as much fuel as it takes to maintain body temperature, but you may not even notice, because you'll do other things to keep warm instead. Come to think of it, accumulating an insulating layer of fat will also dampen the effect.
CICO is about as helpful as MIMO -- matter in, matter out. In is easy to measure, out not at all easy.
There is obviously thermodynamic energy in food which is not absorbed in the gastrointestinal tract. Fiber is an example of this. Energy which is not absorbed is not listed on the nutrition label of food. When I say 'calories', I mean the biochemically available energy in absorbed macronutrients such as fat, carbohydrates, protein and alcohol.
Nobody doubts that thermogenesis uses energy. This is a special case of my mechanism 3. It is part of the 'energy used'. Again, if you want to convince me that you can eat 3000 calories of fat without gaining weight, you would have to make an argument that the proportion of fat in my diet has a causal effect on thermogenesis, ie, that my body will start running additional thermogenesis because I ate fat instead of carbohydrates.
Your claim that CICO is as helpful as MIMO is clearly ridiculous, and if you truly believe this, then supermodels eating tissue paper are more rational than you, as their beliefs will lead to more accurate predictions.
The point I am trying to make is that our body is an efficient engine due to evolutionary pressure, that energy doesn't just disappear (if it did, we would observe large amounts of unmetabolized macronutrients in urine), and that even if CICO is not the whole picture, it explains a very large part of the variation in body weight observed in human populations
On a previous occasion when this topic came up, I posted this anecdote.
Now, as you might imagine, there were medical reasons for that episode. Or rather, there were concurrent medical events with no obvious connection: acute ulcerative colitis, a disease of the large intestine only. Most nutrition is extracted by the stomach and small intestine, which were unaffected. So what was going on there? What made my digestive system so inefficient for several years following the initial attack?
So there's a lot of room for variation in digestive efficiency.
(For those who know the last-resort treatment for ulcerative colitis, I'll just add that I recovered without surgery.)
What is more ridiculous about MIMO than CICO? Conservation of matter, can't argue with that.
You don't get to be a supermodel unless you can stay thin. Some people can, no-one doubts that, and some people just are, without taking any effort. And I'll take Eliezer's word that nothing has worked for him over anyone's assertion that because they can't see how something could happen, it doesn't happen. CICO is only one part of the picture, and its abundantly clear from experiences of dieting that it's of little explanatory value on its own, and of practical value to only a subset of people.
OK, I see the point. But multicellular life evolved as thermodynamic engines, not as fusion plants. Over billions of years, cells were surviving based on how efficiently they could extract thermodynamic energy from macronutrients, to power intracellular processes. This is what we are optimized for. If we had been able to use fusion power in our evolutionary past, MIMO would be a more appropriate level at which to draw your map.
It all depends on what you mean by "very good approximation." There's an entire cottage industry in medicine that revolves around developing weight prediction models; none of them get good results even assuming one knows much more data than simply calorie intake.
I suspect this is possibly the source of a few downvotes. Since this is superficially a site on rationality and science, every once in a while the doctrine of Calories In, Calories Out (CICO) rears it's ugly head. People who have actually looked into the situation know that it's a drastic oversimplification, but experience has shown it's usually not worthwhile to convince adherents of CICO of the complexity of the problem.
Here is a list of some violations of CICO.
Thank you, that was helpful.
Note that I don't disagree with anything in that Mayo Clinic article. The point about "pounds of fat, muscle and water" is obviously true and does not contradict anything I said. The points about "metabolic rate" and "response to reduced calories" just seem to say that sometimes it is difficult to estimate the "calories out" part of the equation, and that it is endogenous to the system. This is also obviously true. I still find it difficult to believe that we can affect the metabolic rate to an extent that matters in the final analysis, based on the fat/protein/carbohydrate content of our diet..
Did I misunderstand your grandparent post? It sounded like you were looking for an explanation as to why CO is hard to quantify.
I disagree that this is a fair rephrasing of the article. A correct rephrasing would be "It is always difficult to estimate the CO part of the equation."
What would convince you otherwise? When I posted my grandparent response, I wasn't in a position to link to the various body weight modelling studies that have been done, but I could do so if you'd think it might convince you.
OK. I'll accept your rephrasing. Let us assume that "calories out" is always difficult to estimate and depends on a lot of factors such as muscle mass and total calorie intake.
I took the original comment to mean that we can eat very large amounts of fat and protein, because our bodies would somehow react, in response to the proportion of different nutrients in our diet, and change how efficiently we use energy. I find it difficult to believe that this would explain much of change in body weight. I find it much easier to believe that it would change our appetites and thus reduce calorie intake.
I am certainly willing to update my priors if someone convinces me of a plausible mechanism by which proportion of each nutrient alters efficiency of energy use..
Comments which mention the importance of calories are reflexively downvoted around here.
I think many people are confused between what CICO actually says (your energy balance determines your weight loss or gain) and what their image of CICO -- conveniently made out of straw -- says (there is a magic fixed number of calories, if you eat less than that magic number you'll lose weight).
Typically the conversations are downvoted based on the actual expressed claims in those comments. Most people who make thermodynamics references do in fact say stupid things out of ignorance.
My limited experience -- that is, actual empirical data available to me -- suggests this is not the case when the topic is CICO.
Most people who mention dieting or human metabolism do in fact say stupid things out of ignorance.
I had noticed this. Personally, I'm very confused about the causes-of-obesity issue. To me it's obvious that if you eat less or burn more, you will lose weight. It's complicated by regulatory mechanisms; eating less causes your body to conserve energy by slowing the metabolism, and physical exercise increases appetite. And I think it's likely there are genetic set points that affect both body type (weight) and appetite. Then there's the fidgeting thing. Then there are the low/high carb theories and studies where weight is modulated by changes in regulatory pathways, and the "fructose poisoning causes fatty liver causes metabolic dysfunction" theory. And stuff like "metabolic syndrome" and Type 2 diabetes. Then there are people who are fat and eat half what I do. In the end, I have no idea how the human body regulates weight and calorie intake, but my body seems to do it fine.
Well, it is complicated.
Think of weight regulation as a three-layered cake :-)
The bottom layer is physics and CICO holds. The only way to lose weight is to spend more energy than you consume.
The middle layer is biochemistry. CICO still holds, but the energy output is a function of a large number of inputs (from genetic makeup to what kind of food do you eat). All the metabolic issues, insulin, leptin, ketosis, etc. live here.
The top layer is the mind. CICO still holds and all the biochemical mechanisms from the middle layer still hold, but now we add all the mental stuff -- preferences, compulsions, eating-for-comfort, anorexia, eating as a displacement mechanism, etc.
And the cherry on top is that people are different. They have different metabolisms which work in different ways, they react differently to the same stimuli. No solution works for everyone and it looks likely that no solution even works for most. The only way out is to personally experiment and find out what works for you, for your personal, unique, and strange body and mind.
And we haven't even touched the question of whether weight is the right metric to use (consider the alternatives, e.g. body fat % or general health even understood in a limited sense as absence of disease and normal metabolic markers).
So yeah, complicated it is.
Liposuction.
The laws of thermodynamics don't require a fat cell to release lipids because you're hungry or exercising; the fat cells can just physically not react until your muscles run out of glucose or your brain overrules your attempt to starve yourself to death. Similarly, there's no rule that fat cells can't die or shrink and the waste be dumped out through urine.
Thermodynamics is not any more useful than quantum mechanics in understanding obesity. It is moralizing disguised as an invocation of natural law.
I think this can actually happen to a very great extent depending on how much the person normally eats and burns, and how quickly they consume it, and is the main mechanism by which e.g. competitive eaters generally avoid becoming obese.
By which mechanism do these nutrients get excreted? Urine? Bile? Non-absorption?
My impression is that carbohydrates in urine is something that we only see to a significant extent when blood glucose concentration is at diabetic levels. Protein and fat in urine occurs, but it doesn't seem to me that this happens to an extent where it can make a difference to the total energy picture
I don't think excreting them through bile would work, the nutrients would just be reabsorbed further down the gastrointestinal tract.
It is possible that at very high intake levels, there is significant non-absorption of fat. Maybe this happens in competitive eaters, but I am not convinced it can explain much at fat intake levels seen in ordinary people..
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1793018/
(Bam.) So, under normal conditions you're pretty efficient (~4% of your calories just get pooped back out), meaning that something like metabolic rate just swamps poop-energy-content as an interpersonal variable.
This article says that there is some non-absorption of fat in healthy people, and much greater non-absorption in people with cystic fibrosis.
If you want to convince me that I should consider this when I choose the fat/carbohydrate/protein content of my diet, you would have to make an argument that the percentage of fat that is not absorbed is a function of my diet, ie, causally related to what I choose to eat.
I'm not saying this is not theoretically possible, but my intuition tells me that the variation in absorbtion that is caused by diet, is unlikely to have a major impact in the final analysis
I can't think of any way to answer you correctly and yet also briefly, because Taubes's ideas are not easy, at least not easy for me, to put into a nutshell.
Therefore what I am about to say should be taken as no more than a very crude, and greatly exaggerated, approximation of Taubes's theory. Here it is: if you eat more carbs, you turn yourself into a Zucker rat. If you eat fewer carbs, you stop being a Zucker rat.
What is a Zucker rat? I'll let Taubes describe the Zucker rat:
I suppose the point is less that you can lose weight on 3000 carb-free calories a day, and more that you can't lose weight if you're eating carbs.
Just out of interest, what's the proposed mechanism by which carbs turn us into Zucker rats?
Briefly and crudely, carbs affect insulin, insulin affects how greedy and stingy the fat cells are. Greedy fat cells grab energy-carrying molecules, effectively starving the rest of the body. Stingy fat cells are reluctant to let go of the energy they've stored, keeping the rest of the body starved. A starved body is simultaneously hungry and lethargic, for obvious reasons. This in effect reverses the usual causal picture. Greedy stingy fat cells cause a person to feel hungry and lethargic, which causes a person to be inactive and eat a lot. The picture that most people have in their minds is the reverse: a person who eats a lot and who exercises little will, as a consequence of these two vices, get fat. Taubes argues that these so-called vices are a symptom of starvation, which is caused by fat cells hoarding energy, which in turn is caused primarily by high insulin. To break the vicious cycle, cut out the part of the food which spikes insulin, and that is primarily the carbs, and specifically certain kinds of carbs which are rapidly digested.
To repeat, while I'm trying to give the best answer I can, it's only an approximation of his argument.
Based on what I know about biochemistry and metabolism, that sounds reasonable. Have they done any studies on humans (not mice)?
Taubes wrote a 600-page book on the science, most of it involving humans. I'm out of my depth at this point - you would need to consult the book, either Good Calories Bad Calories, or one he wrote more recently for a wider audience that seriously trims back on the science. But if you want the science you want the earlier, bigger book.
The amazing thing (to me) is that Taubes' two books are not original or personal studies, nor does he claim otherwise. Instead, they are exhaustive reviews of the published dietary research, in which he looks at what was found, and the conclusions that should be drawn. It is (in my opinion) one of the most egregious examples of confirmation bias that the establishment researchers and the government (USA) chose to conclude from these same studies those things that supported their established views, in spite of their own evidence to the contrary. I conclude that adoption of Taubes' findings into our lifestyles would have more positive impact on healthcare (at least, in the USA) than anything else I know. I acknowledge that SIAI President Michael Vassar has said to me: "I met Taubes and he seemed (almost certainly) sincere but not all that bright. Definitely not very erudite and not all that good at philosophy of science." I suggest that readers review Taubes' credientials and determine, as I have, whether he is likely qualified both to understand and to write about the topic. I have been an Atkins devotee for years, and my chemistries reflect Taubes' conclusions (anecdotal). I acknowledge that some very intelligent people (e.g. Yudkowsky) believe that some particular individuals are mysteriously "metabolically challenged", and may respond differently, although I am not aware of the studies to confirm this.
I'm not a nutritionist, but the theory as I understand it is that shifting the balance of calories away from carbohydrates primes your metabolism by changing the pattern of insulin secretion, making your body more likely to break down its stored fats in order to keep blood glucose levels up.
High-fat, high-protein foods also tend to feel more filling for a given number of calories, and leafy vegetables are physically bulkier, which might also contribute to their perception as less fattening.