I fail to see any arguments why we cannot use thermodynamics (calorie input/output) as a very good approximation of predicted weight change.
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.
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.
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.
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.”
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.
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..
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..