I didn’t downvote you, I think you are eloquently arguing your point here! But I’m not entirely sure that the SMTM take is quite as bad as you make it out to be.
An average of 400 extra calories a day isn’t small on its own, but I think the SMTM argument is that it’s small compared to historical variation in caloric intake, and small compared to variation among humans in general today. In other words: there were likely times and cultures historically where average calories consumed was higher or lower than today by more than 400 calories—why wasn’t there an obesity epidemic previously when caloric intake was higher? Why, 100 years ago, were not the people eating 400 extra calories a day all obese?
I clearly found it more a more compelling argument that you do. Like you, I read the SMTM contaminant argument as essentially saying “historically there has been some process that kept calories consumed and calories expended in relative sync; that process has been disrupted”—and the argument that “400 calories per day explains the weight gain” isn’t really a counterargument to this?
I’ll point out one more aspect that I think you may want to consider. You write: “to me it’s quite obvious that in the long run more calorie intake has to lead to higher body mass”—but this is a statement that is somewhat circularly derived from today’s observations. 100 years ago, when very few people were obese, this statement might not be obvious at all. One might instead conclude that people with higher calorie intakes are compelled to burn more calories through manual labor, exercise, heat generation + sweating, etc.
Lastly, and obviously you know this on some level, but the fact that increased food consumption correlates with obesity, does not imply that that consumption causes obesity. SMTM argue that some external factor causes obesity; if so, increased food consumption would be a result of the body trying to maintain that weight. As you note, a 15% increase in body mass requires a 20% increase in caloric intake to sustain—if an external factor is increasing the lipostat, we would observe exactly what we observe today as well. It’s dangerous to point the causal arrow in either direction without more evidence.
And, speaking of evidence: the overfeeding studies are interesting in part because they at least resolve the question of whether and how much short-term overeating causes body mass increases; you’re 100% correct that they don’t resolve the question of whether long-term overeating also causes body mass increases, and it would be super interesting to see if a long-term (say, 1 year) 400-calorie increase in consumption (that somehow doesn’t come from changes in diet; maybe just eat an extra 20% at every meal?) causes weight gain.
As far as I know, no one’s run a long-term weight gain study—but we do have the super confusing result that a 30-40% decrease in calories is hard to sustain and the resulting weight loss plateaus at about a 10% decrease [0], suggesting that there’s more going on than the simple linear relation.
An average of 400 extra calories a day isn’t small on its own, but I think the SMTM argument is that it’s small compared to historical variation in caloric intake, and small compared to variation among humans in general today. In other words: there were likely times and cultures historically where average calories consumed was higher or lower than today by more than 400 calories—why wasn’t there an obesity epidemic previously when caloric intake was higher? Why, 100 years ago, were not the people eating 400 extra calories a day all obese?
Variation among humans can be caused by variation in their metabolism (or variation in how much they exercise) that changes the amount of energy they expend per unit mass without being inconsistent with the energy balance argument. There’s a lot of place variation in the cross section can come from other than calories consumed—I don’t think that’s actually that relevant to understanding trends in obesity. Energy balance can hold at any level of calorie intake so the question is why you settle on one point of equilibrium and not all the others, given that you’re the one making the decisions about how much to eat.
As for historical data, I’m not convinced there’s ever been a time when mean calorie intake in a reasonably large country was ever as high as it is in the US today. There’s of course been plenty of variation but I’d expect the variation to show up in body mass if it were sustained.
I clearly found it more a more compelling argument that you do. Like you, I read the SMTM contaminant argument as essentially saying “historically there has been some process that kept calories consumed and calories expended in relative sync; that process has been disrupted”—and the argument that “400 calories per day explains the weight gain” isn’t really a counterargument to this?
I’m not really convinced by the claim that what’s happening now is historically unprecedented and I think most of the work there is being done by summarizing the phenomenon in terms of obesity statistics instead of mean body mass. I think if we looked at the historical trajectory of mean body mass it would not really look like anything exceptional is happening today in terms of some fundamental balance process being thrown off.
I want to repeat: the point of my comment is not that “why are people eating more now?” is a question that shouldn’t be answered; it’s that the claim about 400 kcal being too small of an increase is just wrong. If you agree with that then you should just agree with my comment because that’s the only claim I make.
As far as I know, no one’s run a long-term weight gain study—but we do have the super confusing result that a 30-40% decrease in calories is hard to sustain and the resulting weight loss plateaus at about a 10% decrease [0], suggesting that there’s more going on than the simple linear relation.
I think my argument says nothing about how hard to sustain a decrease in calorie intake is—it’s consistent with your body making arbitrarily strong protests at having to burn its stores of fat and try to induce you to eat more to compensate. I’m agnostic on that point and I think it’s obviously an interesting question to look into.
Farm laborers historically ate a lot of calories just to be able to get through their days. Their calories weren’t very appetizing, but they had to eat a lot because they burned a lot.
That makes sense to me but I’d really need to see the data on how many calories they ate in 1700. I notice I would still be surprised if an average farm laborer in 1700 in prime age ate more than 2400 kcal/day. It’s not really relevant to my main point but if you have some data proving that I would be interested to see it.
Per Jeffrey L. Singman, Daily Life in Medieval Europe, Westport, Connecticut: Greenwood Press, 1999, P. 54 − 55 (and text copied from https://stores.renstore.com/food-and-drink/dietary-requirements-of-a-medieval-peasant), “A prosperous English peasant in the 14th century would probably consume 2 − 3 pounds of [rye, oats, or barley] bread, 8 ounces of meat or fish or other protein and 2 − 3 pints of ale per day”, which works out to about 3500 to 5000 calories per day.
That same page lists various farm chores as burning 1500-7500 calories over an 8 hour period, so assuming some mix of those plus the normal base calorie burning easily adds up to over 3500 calories.
This post (https://oureverydaylife.com/321257-the-peasant-diet.html) cites “research published at Eastern Kentucky University” to say that “an average medieval person burned between 4,000 and 5,000 calories per day … A typical diet for peasants delivered between 3,500 and 4,500 calories, about or just under the need.”
If you’d like I can do more academic research, but these independent sources all roughly corroborate each other so I’m personally satisfied.
One note is that the food eaten historically was much less appealing to eat. I don’t think they were eating 3 pounds of bread because they really liked oat bread, but rather that they needed it to survive doing hard manual labor for 8 hours a day.
Reported numbers vary quite a bit (perhaps in part because the physical activity intensity of training or warfighting also varies), but you might be interested to know that soldiers in training or active duty might hit something like 4000-5000 kcal/day in energy expenditure, maybe thousands more for outlier people and/or circumstances.
How much did city dwellers in the early 20th century eat? There must have been a period when people were not doing so much manual labor but before the obesity epidemic.
A lot of city dwellers then were doing manual labor (factory lines, construction), but I’m really not sure about the office workers from them. It’s a good question!
I think you are missing my point—which EY also makes above—that you are concluding that the calorie consumption increase causes obesity when in fact none of the evidence you provide supports pointing the causal arrow in that direction specifically.
We know obese people eat more, and we know that the greater fat mass has greater nutritional requirements.
The interesting question is not whether 400 calories are associated with the weight gain, clearly people are more obese now and also they eat 400 more calories on average, no one is disputing this. The interesting question is whether those 400 calories cause the weight gain or are caused by the weight gain. You are implying the former but there is not a lot of evidence in support of it—and other posters in this thread are chiming in with other evidence suggesting that 400 calories daily is well within normal historical variation, which is SMTM’s point that “400 extra calories causes weight gain” would be weird.
I think you are missing my point—which EY also makes above—that you are concluding that the calorie consumption increase causes obesity when in fact none of the evidence you provide supports pointing the causal arrow in that direction specifically.
No I’m not. I don’t understand why people are jumping to this conclusion—I said several times that “the only claim I’m making is X” but people keep attributing to me claims that are not X.
The interesting question is not whether 400 calories are associated with the weight gain, clearly people are more obese now and also they eat 400 more calories on average, no one is disputing this. The interesting question is whether those 400 calories cause the weight gain or are caused by the weight gain.
As I’ll repeat here again, the whole point of my comment is to question SMTM’s claim that a 20% increase in calorie intake is small. It’s not small. I agree otherwise that the interesting question is what caused people to shift from one equilibrium to another and talking about energy balance doesn’t help clear up that point. It’s just not the point I’m trying to make, though.
I think we are getting caught up in the definition of “small”. My original point earlier is that 400 calories is small compared with historical variation and variation among humans. Your original point is that 400 calories is more than enough to explain the weight gain and thus isn’t “small”. Those are different definitions of small, and are both true: 400 calories is small compared with historical and present variation among humans AND 400 calories is enough to explain the extra weight.
But the latter is obvious; clearly those 400 calories explain the weight gain, because people aren’t suddenly metabolizing air or water or other calorie-free inputs into extra weight, those fat cells are creating fat from calories people consume. I suspect people are ascribing other claims to you because “400 calories is not small—it’s enough to explain the excess weight” is only a useful claim in this context (“this context” being “what causes obesity?”) if you are also making the causative claim.
You insist you are not making the causative claim—so what exactly are you arguing re: the question of “what’s causing the weight gain?”
I didn’t downvote you, I think you are eloquently arguing your point here! But I’m not entirely sure that the SMTM take is quite as bad as you make it out to be.
An average of 400 extra calories a day isn’t small on its own, but I think the SMTM argument is that it’s small compared to historical variation in caloric intake, and small compared to variation among humans in general today. In other words: there were likely times and cultures historically where average calories consumed was higher or lower than today by more than 400 calories—why wasn’t there an obesity epidemic previously when caloric intake was higher? Why, 100 years ago, were not the people eating 400 extra calories a day all obese?
I clearly found it more a more compelling argument that you do. Like you, I read the SMTM contaminant argument as essentially saying “historically there has been some process that kept calories consumed and calories expended in relative sync; that process has been disrupted”—and the argument that “400 calories per day explains the weight gain” isn’t really a counterargument to this?
I’ll point out one more aspect that I think you may want to consider. You write: “to me it’s quite obvious that in the long run more calorie intake has to lead to higher body mass”—but this is a statement that is somewhat circularly derived from today’s observations. 100 years ago, when very few people were obese, this statement might not be obvious at all. One might instead conclude that people with higher calorie intakes are compelled to burn more calories through manual labor, exercise, heat generation + sweating, etc.
Lastly, and obviously you know this on some level, but the fact that increased food consumption correlates with obesity, does not imply that that consumption causes obesity. SMTM argue that some external factor causes obesity; if so, increased food consumption would be a result of the body trying to maintain that weight. As you note, a 15% increase in body mass requires a 20% increase in caloric intake to sustain—if an external factor is increasing the lipostat, we would observe exactly what we observe today as well. It’s dangerous to point the causal arrow in either direction without more evidence.
And, speaking of evidence: the overfeeding studies are interesting in part because they at least resolve the question of whether and how much short-term overeating causes body mass increases; you’re 100% correct that they don’t resolve the question of whether long-term overeating also causes body mass increases, and it would be super interesting to see if a long-term (say, 1 year) 400-calorie increase in consumption (that somehow doesn’t come from changes in diet; maybe just eat an extra 20% at every meal?) causes weight gain.
As far as I know, no one’s run a long-term weight gain study—but we do have the super confusing result that a 30-40% decrease in calories is hard to sustain and the resulting weight loss plateaus at about a 10% decrease [0], suggesting that there’s more going on than the simple linear relation.
[0] https://www.nejm.org/doi/full/10.1056/NEJMoa2114833
Variation among humans can be caused by variation in their metabolism (or variation in how much they exercise) that changes the amount of energy they expend per unit mass without being inconsistent with the energy balance argument. There’s a lot of place variation in the cross section can come from other than calories consumed—I don’t think that’s actually that relevant to understanding trends in obesity. Energy balance can hold at any level of calorie intake so the question is why you settle on one point of equilibrium and not all the others, given that you’re the one making the decisions about how much to eat.
As for historical data, I’m not convinced there’s ever been a time when mean calorie intake in a reasonably large country was ever as high as it is in the US today. There’s of course been plenty of variation but I’d expect the variation to show up in body mass if it were sustained.
I’m not really convinced by the claim that what’s happening now is historically unprecedented and I think most of the work there is being done by summarizing the phenomenon in terms of obesity statistics instead of mean body mass. I think if we looked at the historical trajectory of mean body mass it would not really look like anything exceptional is happening today in terms of some fundamental balance process being thrown off.
I want to repeat: the point of my comment is not that “why are people eating more now?” is a question that shouldn’t be answered; it’s that the claim about 400 kcal being too small of an increase is just wrong. If you agree with that then you should just agree with my comment because that’s the only claim I make.
I think my argument says nothing about how hard to sustain a decrease in calorie intake is—it’s consistent with your body making arbitrarily strong protests at having to burn its stores of fat and try to induce you to eat more to compensate. I’m agnostic on that point and I think it’s obviously an interesting question to look into.
Farm laborers historically ate a lot of calories just to be able to get through their days. Their calories weren’t very appetizing, but they had to eat a lot because they burned a lot.
That makes sense to me but I’d really need to see the data on how many calories they ate in 1700. I notice I would still be surprised if an average farm laborer in 1700 in prime age ate more than 2400 kcal/day. It’s not really relevant to my main point but if you have some data proving that I would be interested to see it.
Per Jeffrey L. Singman, Daily Life in Medieval Europe, Westport, Connecticut: Greenwood Press, 1999, P. 54 − 55 (and text copied from https://stores.renstore.com/food-and-drink/dietary-requirements-of-a-medieval-peasant), “A prosperous English peasant in the 14th century would probably consume 2 − 3 pounds of [rye, oats, or barley] bread, 8 ounces of meat or fish or other protein and 2 − 3 pints of ale per day”, which works out to about 3500 to 5000 calories per day.
That same page lists various farm chores as burning 1500-7500 calories over an 8 hour period, so assuming some mix of those plus the normal base calorie burning easily adds up to over 3500 calories.
This blog post (https://www.worldturndupsidedown.com/2011/08/how-many-calories-did-they-eat-in-day.html?m=1) looked at a shopping list from the 1860s and found that men ate about 3500 calories per day while women ate about 2500 calories per day. I’m not sure what audience this was aimed at (farmers? factory workers?) but clearly it’s more than 2400 calories per day.
This post (https://oureverydaylife.com/321257-the-peasant-diet.html) cites “research published at Eastern Kentucky University” to say that “an average medieval person burned between 4,000 and 5,000 calories per day … A typical diet for peasants delivered between 3,500 and 4,500 calories, about or just under the need.”
If you’d like I can do more academic research, but these independent sources all roughly corroborate each other so I’m personally satisfied.
One note is that the food eaten historically was much less appealing to eat. I don’t think they were eating 3 pounds of bread because they really liked oat bread, but rather that they needed it to survive doing hard manual labor for 8 hours a day.
Thanks, that’s interesting. Intuitively I would not have expected them to be burning so many calories.
Reported numbers vary quite a bit (perhaps in part because the physical activity intensity of training or warfighting also varies), but you might be interested to know that soldiers in training or active duty might hit something like 4000-5000 kcal/day in energy expenditure, maybe thousands more for outlier people and/or circumstances.
How much did city dwellers in the early 20th century eat? There must have been a period when people were not doing so much manual labor but before the obesity epidemic.
A lot of city dwellers then were doing manual labor (factory lines, construction), but I’m really not sure about the office workers from them. It’s a good question!
I think you are missing my point—which EY also makes above—that you are concluding that the calorie consumption increase causes obesity when in fact none of the evidence you provide supports pointing the causal arrow in that direction specifically.
We know obese people eat more, and we know that the greater fat mass has greater nutritional requirements.
The interesting question is not whether 400 calories are associated with the weight gain, clearly people are more obese now and also they eat 400 more calories on average, no one is disputing this. The interesting question is whether those 400 calories cause the weight gain or are caused by the weight gain. You are implying the former but there is not a lot of evidence in support of it—and other posters in this thread are chiming in with other evidence suggesting that 400 calories daily is well within normal historical variation, which is SMTM’s point that “400 extra calories causes weight gain” would be weird.
No I’m not. I don’t understand why people are jumping to this conclusion—I said several times that “the only claim I’m making is X” but people keep attributing to me claims that are not X.
As I’ll repeat here again, the whole point of my comment is to question SMTM’s claim that a 20% increase in calorie intake is small. It’s not small. I agree otherwise that the interesting question is what caused people to shift from one equilibrium to another and talking about energy balance doesn’t help clear up that point. It’s just not the point I’m trying to make, though.
I think we are getting caught up in the definition of “small”. My original point earlier is that 400 calories is small compared with historical variation and variation among humans. Your original point is that 400 calories is more than enough to explain the weight gain and thus isn’t “small”. Those are different definitions of small, and are both true: 400 calories is small compared with historical and present variation among humans AND 400 calories is enough to explain the extra weight.
But the latter is obvious; clearly those 400 calories explain the weight gain, because people aren’t suddenly metabolizing air or water or other calorie-free inputs into extra weight, those fat cells are creating fat from calories people consume. I suspect people are ascribing other claims to you because “400 calories is not small—it’s enough to explain the excess weight” is only a useful claim in this context (“this context” being “what causes obesity?”) if you are also making the causative claim.
You insist you are not making the causative claim—so what exactly are you arguing re: the question of “what’s causing the weight gain?”