Sorry, I specifically meant the studies you list under the “Lithium weight gain seems to (perhaps) be dose-dependent even at therapeutic doses” section, which is what I was focused on when I wrote my comment. My bad for not being clear.
I’m skeptical of how much we can learn from the Texas study. If harder tap water causes people to drink more bottled water, that could explain the negative correlation.
However, I do think the study showing a lack of correlation between lithium and BMI is important, and cuts strongly against the argument I was making. I would expect to see a striking correlation there if large relative variations at low absolute levels of dietary lithium were an important mechanism contributing to obesity. That’s just not the case.
My only reservation is that we’re trying to answer SMTM’s hypothesis using studies that weren’t specifically designed to test it. I don’t feel confident enough to completely dismiss the idea based on this alone. However, I do think it’s substantially more fragile than I thought before I took this into account. Epistemic status: blowin’ in the wind.
Update: I found a few papers from villages in Argentina with very high lithium exposure, one of which (whose subjects had urinary lithium concentrations ranging from 0.1-14 mg/L) found a positive association between lithium excretion and BMI (r=0.11), and did find that at such levels lithium increased plasma TSH levels. But only 17% of participants were obese,[1] even though the average urinary concentration was > 4 mg/L.
In the other one (which I think I’d seen before, actually) serum lithium concentration (which strongly correlated (0.84) with urinary excretion) was not found to be associated with BMI. The range of urinary concentration was 0.105–4.600 mg/L. Interestingly, higher exposure seemed to have been associated with smaller body size (both height and weight) for the adults in the study as well as the newborn children. The obesity rate among adults in this sample is only 7%.
Those kind of mixed results don’t seem to paint a compelling picture of dietary lithium-induced obesity. So I’m roughly where I was last we exchanged, when you highlighted the lack of serum lithium and BMI correlation in the other study.
In this case, the thing that jumps out at me is that these are studies in Argentinian villages, with people of Indigenous backgrounds eating relatively traditional and likely constrained diets, perhaps with a higher level of compulsion to work than in wealthier areas.
all women almost exclusively drank tap water, their diets (mainly corn, beans, chicken, and pork) were very similar, and only 3 of 202 women reported ongoing use of any medication
The mechanism that seemed most likely to me was that lithium increases both thirst and fatigue (perhaps mediated via subclinical hypothyroidism), leading to increased consumption of sugary beverages in areas with a lot of soda pop around, and decreased activity levels when a sedentary lifestyle is tractable. Since in these areas, the soda pop and sedentary lifestyles are perhaps less available, this might prevent lithium from showing up more strongly as a driver of obesity. If lithium is driving obesity through thirst and sedentary behavior, the women of SAC may just be satisfying their thirst with water and being stuck working even when they’re very tired.
I’d need more data on how obesity rates vary from village to village in this region to know if 17% is low or high. This study in the same village (San Antonio de los Cobres) found an 11% obesity rate among schoolchildren, as compared to 35% in the USA. That’s just to say that we may be looking at a different overall diet/lifestyle/genetic/contaminant reference class than we see in the USA as a whole.
All that said, I don’t see lithium and obesity leaping out of the data. It’s possible that an abundance of diverse low-level environmental contaminants is responsible, with lithium just one of many. Hence, harvesting data from studies looking at specific individual contaminants won’t ever solve the whole puzzle. “It’s probably not the lithium,” but maybe it’s the lithium + 999 other chemicals? Perhaps having a bunch of weird industrial chemicals floating around in the air, water, soil, and food affects people’s metabolism and energy by hammering at all sorts of different bodily systems—inflammation, hunger, mood, who knows what else?
If the explanation is just “a thousand weird chemicals, each with a small and possibly interacting effect across diverse bodily systems making you tired, hungry and thirst” we’d have to ask why, on average, exposure to random chemicals makes you fat and hungry rather than thin and satiated. Perhaps the brain sends hunger and thirst signals when it’s out of whack, on the off chance that the reason it’s having problems is lack of energy? Certainly it makes sense to me that overall, bodily contamination causes fatigue rather than an increase in energy and drive. And I would also expect that the body’s ability to continue extracting nutrients from whatever food you put into it is pretty robust, since that’s mission-critical. So “body gets a chemical shock, guesses hunger/thirst is the cause, can’t maintain focused energy due to chemical interference, still absorbs nutrients and turns them into fat” as explanation?
And what sort of study would we run or look for to investigate this extremely messy hypothesis?
But I have to admit that “people have more junk food and time on their hands, so people sit around, pig out, and get fat” is also a pretty compelling explanation for the obesity epidemic. The only issue is that McDonald’s has been around since 1940, the country’s been wealthy and working desk jobs for a long time, but obese adults were < 15% of the population in most US states in 1990, but 36 states have obesity rates at 25%+. It could be generational decay in how people spend their time and how they eat. But that is getting handwavey in the same way that the contaminant hypothesis is handwavey.
As a followup, the portrait I painted of “chemically-induced tired brain misfiring syndrome”-induced obesity (CITBMS-obesity) seems to suggest a link between obesity and depression would be associated. There does appear to be a link or a U-shaped association between BMI and depression (I’ve only scanned the abstracts).
And as I understand it, we can totally have a CITMBS-obesity epidemic and also a CITMBS-underweight problem at the same time. “Chemically induced weight dysregulation” might be what we’d be looking at.
In such a case, actually, that might make it hard to use the studies we’ve looked at so far to gain information. If the curve is U-shaped, the two ends of the curve may cancel out when averaged together and disguise the effect.
I hadn’t thought of that before. Now my credences for lithium and contamination are back up. It doesn’t completely jive with the story I was telling earlier—now we have a piece where, perhaps, the chemically stressed brain gets hungry/thirsty in some people and loses appetite in others. Both seem plausible. I guess we’d want to look for a relationship between lithium (or other contaminants) and extremes of weight, rather than a correlation between BMI and lithium concentration.
In such a case, actually, that might make it hard to use the studies we’ve looked at so far to gain information. If the curve is U-shaped, the two ends of the curve may cancel out when averaged together and disguise the effect.
Note that this does not seem to be what has happened at a population level in the US. BMI seems to have increased pretty much at all levels — even the 0.5th percentile has increased from NHANES I (in the early 70′s) to the 2017-March 2020 NHANES, as has the minimum adult BMI. And the difference is not subtle.
For instance, here are the thinnest people in the last NHANES versus the first one:
Psychological health impact of chronic environmental contamination is understudied… The meta-analyses observed small-to-medium effects of experiencing CEC on anxiety, general stress, depression, and PTSD. However, there was also evident risk of bias in the data.
So not impossible? And perhaps there are methodologies here that could be useful for looking more broadly at a CEC theory of obesity?
Sorry, I specifically meant the studies you list under the “Lithium weight gain seems to (perhaps) be dose-dependent even at therapeutic doses” section, which is what I was focused on when I wrote my comment. My bad for not being clear.
I’m skeptical of how much we can learn from the Texas study. If harder tap water causes people to drink more bottled water, that could explain the negative correlation.
However, I do think the study showing a lack of correlation between lithium and BMI is important, and cuts strongly against the argument I was making. I would expect to see a striking correlation there if large relative variations at low absolute levels of dietary lithium were an important mechanism contributing to obesity. That’s just not the case.
My only reservation is that we’re trying to answer SMTM’s hypothesis using studies that weren’t specifically designed to test it. I don’t feel confident enough to completely dismiss the idea based on this alone. However, I do think it’s substantially more fragile than I thought before I took this into account. Epistemic status: blowin’ in the wind.
Update: I found a few papers from villages in Argentina with very high lithium exposure, one of which (whose subjects had urinary lithium concentrations ranging from 0.1-14 mg/L) found a positive association between lithium excretion and BMI (r=0.11), and did find that at such levels lithium increased plasma TSH levels. But only 17% of participants were obese,[1] even though the average urinary concentration was > 4 mg/L.
In the other one (which I think I’d seen before, actually) serum lithium concentration (which strongly correlated (0.84) with urinary excretion) was not found to be associated with BMI. The range of urinary concentration was 0.105–4.600 mg/L. Interestingly, higher exposure seemed to have been associated with smaller body size (both height and weight) for the adults in the study as well as the newborn children. The obesity rate among adults in this sample is only 7%.
their average age was 37, median 34, and at that age people are pretty close to the highest BMI they’ll ever have, according to NHANES data.
Very interesting, thanks for finding them.
Those kind of mixed results don’t seem to paint a compelling picture of dietary lithium-induced obesity. So I’m roughly where I was last we exchanged, when you highlighted the lack of serum lithium and BMI correlation in the other study.
In this case, the thing that jumps out at me is that these are studies in Argentinian villages, with people of Indigenous backgrounds eating relatively traditional and likely constrained diets, perhaps with a higher level of compulsion to work than in wealthier areas.
The mechanism that seemed most likely to me was that lithium increases both thirst and fatigue (perhaps mediated via subclinical hypothyroidism), leading to increased consumption of sugary beverages in areas with a lot of soda pop around, and decreased activity levels when a sedentary lifestyle is tractable. Since in these areas, the soda pop and sedentary lifestyles are perhaps less available, this might prevent lithium from showing up more strongly as a driver of obesity. If lithium is driving obesity through thirst and sedentary behavior, the women of SAC may just be satisfying their thirst with water and being stuck working even when they’re very tired.
I’d need more data on how obesity rates vary from village to village in this region to know if 17% is low or high. This study in the same village (San Antonio de los Cobres) found an 11% obesity rate among schoolchildren, as compared to 35% in the USA. That’s just to say that we may be looking at a different overall diet/lifestyle/genetic/contaminant reference class than we see in the USA as a whole.
All that said, I don’t see lithium and obesity leaping out of the data. It’s possible that an abundance of diverse low-level environmental contaminants is responsible, with lithium just one of many. Hence, harvesting data from studies looking at specific individual contaminants won’t ever solve the whole puzzle. “It’s probably not the lithium,” but maybe it’s the lithium + 999 other chemicals? Perhaps having a bunch of weird industrial chemicals floating around in the air, water, soil, and food affects people’s metabolism and energy by hammering at all sorts of different bodily systems—inflammation, hunger, mood, who knows what else?
If the explanation is just “a thousand weird chemicals, each with a small and possibly interacting effect across diverse bodily systems making you tired, hungry and thirst” we’d have to ask why, on average, exposure to random chemicals makes you fat and hungry rather than thin and satiated. Perhaps the brain sends hunger and thirst signals when it’s out of whack, on the off chance that the reason it’s having problems is lack of energy? Certainly it makes sense to me that overall, bodily contamination causes fatigue rather than an increase in energy and drive. And I would also expect that the body’s ability to continue extracting nutrients from whatever food you put into it is pretty robust, since that’s mission-critical. So “body gets a chemical shock, guesses hunger/thirst is the cause, can’t maintain focused energy due to chemical interference, still absorbs nutrients and turns them into fat” as explanation?
And what sort of study would we run or look for to investigate this extremely messy hypothesis?
But I have to admit that “people have more junk food and time on their hands, so people sit around, pig out, and get fat” is also a pretty compelling explanation for the obesity epidemic. The only issue is that McDonald’s has been around since 1940, the country’s been wealthy and working desk jobs for a long time, but obese adults were < 15% of the population in most US states in 1990, but 36 states have obesity rates at 25%+. It could be generational decay in how people spend their time and how they eat. But that is getting handwavey in the same way that the contaminant hypothesis is handwavey.
Thanks for finding those studies!
As a followup, the portrait I painted of “chemically-induced tired brain misfiring syndrome”-induced obesity (CITBMS-obesity) seems to suggest a link between obesity and depression would be associated. There does appear to be a link or a U-shaped association between BMI and depression (I’ve only scanned the abstracts).
And as I understand it, we can totally have a CITMBS-obesity epidemic and also a CITMBS-underweight problem at the same time. “Chemically induced weight dysregulation” might be what we’d be looking at.
In such a case, actually, that might make it hard to use the studies we’ve looked at so far to gain information. If the curve is U-shaped, the two ends of the curve may cancel out when averaged together and disguise the effect.
I hadn’t thought of that before. Now my credences for lithium and contamination are back up. It doesn’t completely jive with the story I was telling earlier—now we have a piece where, perhaps, the chemically stressed brain gets hungry/thirsty in some people and loses appetite in others. Both seem plausible. I guess we’d want to look for a relationship between lithium (or other contaminants) and extremes of weight, rather than a correlation between BMI and lithium concentration.
Note that this does not seem to be what has happened at a population level in the US. BMI seems to have increased pretty much at all levels — even the 0.5th percentile has increased from NHANES I (in the early 70′s) to the 2017-March 2020 NHANES, as has the minimum adult BMI. And the difference is not subtle.
For instance, here are the thinnest people in the last NHANES versus the first one:
The relevant Google Colab cells start here.
And then there’s this study: Chronic environmental contamination: A systematic review of psychological health consequences (again, I’m just skimming abstracts).
So not impossible? And perhaps there are methodologies here that could be useful for looking more broadly at a CEC theory of obesity?