= 27d567bc2d48d9f40e9ccc20ea370b15)
paper-machine comments on How I Lost 100 Pounds Using TDT - Less Wrong
You are viewing a comment permalink. View the original post to see all comments and the full post content.
= 783df68a0f980790206b9ea87794c5b6)
Loading…= b715d02e85f7b3b4ae65ca3d3e450868)
Subscribe to RSS Feed
Powered by Reddit
= f037147d6e6c911a85753b9abdedda8d)
You are viewing a comment permalink. View the original post to see all comments and the full post content.
Comments (242)
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.
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..