[i_am_proteus]

I had never heard of slime mold time mold dot com until today, so I read back through the author's theories and I'm not convinced there's anything here.

His initial premise, that the cause of obesity is a mystery, doesn't seem to be that well-researched. Most importantly, he does not really poke holes in the basic premise that the cause is linked to increased availability of food in general coupled with more people living sedentary lifestyles. He even mentions that average daily caloric intake has gone up c. 400 kcal since the turn of the 20th century. Which, for someone with a maintenance-level diet, would cause a 35-45 lb. annual weight gain.

The antibiotic theory here doesn't seem to address the possibility of wealth and industrialization as a confounding variable. In fact, he doesn't seem to seriously address confounding variables anywhere in his analysis.

I don't assert that antibiotics in the food supply should not be considered harmful, but his vague hand-waving in the direction of a culprit for some great unknown mystery seems thin at best. I'd love to hear some competing takes.

[lmilcin]

General availability of food as a driver of obesity is a false premise IMO.

It does not explain a lot of countries where food had been available for well over half a century in any quantity you wanted and yet people don't have problem with obesity.

Saying these countries are somehow "special" because of their cuisine or tradition seems like admitting that something else rather than availability of food is an important influence.

Also one other interesting point is that not all countries see increasing obesity. For example, Canada has not seen significant increase in overweight and obesity since at least early 90s while US seen its rates double during that time.

I don't think anybody will say that food is scarce in Canada.

[armchairhacker]

Also even though starvation was much more common back then, people still had access to excess food and didn’t get fat. Some animals will eat until they literally explode. People have a fullness indicator but we ignore it, or it gets shifted towards eating too much.

I’m on the side that we’re overthinking it and a big contributor to obesity is just really bad cultural habits. A lot of people barely exercise at all, even walking, and when they get hungry they grab an unhealthy snack in 5 seconds. Even though are ancestors didn’t understand or care about exercise or getting fat, I doubt they had those habits.

Unfortunately once someone develops those habits, even as a kid, they’re hard to unlearn and they could affect the body’s set point. And they’re so ingrained into our culture that even people who try to be healthy (e.g. by eating a “healthy” fruit bar or exercising 30min on top of their sedentary lifestyle) don’t avoid them.

Now, there are people who got obese even though they exercise and eat whole foods, but I would be surprised if they aren’t a minority.

[giantg2]

I know plenty of fat vegetarians/vegans. It seems they would not be exposed to those antibiotics.

I remember seeing a Ted Talk years ago where the speaker said that obese people have an issue with androgenesis. His theory was that it was causally linked, but I believe that was unconfirmed.

[teachrdan]

Might vegetarians still be exposed through eggs and dairy products?

[giantg2]

Possibly, but not if they are also eating those items selectively, like organic etc. Some of the vegetarians I know are pretty selective about the treatment of the animals that those items come from. I believe they said organic standards require eggs to be produced by chickens that have some outdoor exposure instead of sitting in cages their whole lives.

[simiones]

> He even mentions that average daily caloric intake has gone up c. 400 kcal since the turn of the 20th century. Which, for someone with a maintenance-level diet, would cause a 35-45 lb. annual weight gain.

That's one data point, but they also show that caloric intake has been decreasing since 2010 and yet obesity is still increasing. They also mention that the 400 Cal figure is based on consumption in the 1960s-70s vs today, but that there are reasons to believe that at the turn of the century consumption would have been higher than that. Also, observing that people are eating more just begs the question: why are they eating more today than they need, when they weren't dong this in the past?

> Most importantly, he does not really poke holes in the basic premise that the cause is linked to increased availability of food in general coupled with more people living sedentary lifestyles.

Except that people are exercising on average more today than in 2010 or 1990, and more than office workers in 1950, and still obesity is going up. Similarly for availability of food. Also, none of your observations address the bizarre correlation between obesity and altitude for example.

> The antibiotic theory here doesn't seem to address the possibility of wealth and industrialization as a confounding variable. In fact, he doesn't seem to seriously address confounding variables anywhere in his analysis.

Industrialization and wealth are not direct causes of obesity - people don't eat money or factories. If people in countries A and B are eating the same amount and composition on average, but country A is wealthy and industrial and country B is poor and rural, and country A has higher average BMI than country B, then you should exactly start looking at some environmental causes for the difference.

Edit to add:

> Which, for someone with a maintenance-level diet, would cause a 35-45 lb. annual weight gain.

This is nonsense - there is no way to predict weight gain based on calorie intake - variance between people is too huge on this metric - individual BMR alone varies between 1000 kcal/day up to 2500 kcal/day.

[Knufen]

>This is nonsense - there is no way to predict weight gain based on calorie intake - variance between people is too huge on this metric - individual BMR alone varies between 1000 kcal/day up to 2500 kcal/day.

Please site your sources. A variance of basal metabolic rate (BMR) of 2500 kcal/day sounds too extreme to be true, but I am open to learning something new. At least according to (https://examine.com/nutrition/does-metabolism-vary-between-t...) the variance in BMR is only around 300-400 kcal/day which makes your number unbelievable high.

[dTal]

Well, with a 35-45 lb. annual weight gain, after 40 years you would literally weigh as much as a car. Obviously that doesn't happen with any regularity, so clearly an equilibrium is reached and the curve flattens off at some relatively modest point. Therefore, the heavier you are, the more food you need to maintain your weight. Asymptotically, calorie intake predicts your final weight, not weight gain.

[simiones]

Note that I meant that BMR can vary between 1100 kcal/day to 2500 kcal/day (so a variance of 1400 kcal/day between individuals), not that it can vary by 2500 kcal/day.

Here are two studies that support slightly smaller numbers than I claimed, but still significantly larger than 300-400.

[0] studied the factors affecting BMR in 150 Scottish adults. It found a variance between ~1100 kcal/day to ~2100 kcal/day between its subjects (for the record, 60% of the variance was attributable to lean body mass).

[1] is a meta-study that looked at RMR (expressed as kcal/kg*h) for adults at various ages. The largest variance from Figure 1 is, assuming all subjects weighed 100kg, the highest RMR would be ~2500 kcal/day, while the lowest would be 1600 kcal/day. Given the varying weights, the actual variance recorded could be bigger or smaller.

In addition to this, even people with the same BMR/RMR eating the same food will not gain the same weight - they may differ in the amount of exercise, or in their calorie calorie consumption while exercising.

[0] https://academic.oup.com/ajcn/article/82/5/941/4607670 [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4535334/

[i_am_proteus]

Industrialization dramatically increases agricultural output, primarily due to use of fossil-fired tractors, harvesters, and irrigation pumps, along with fertilizers (which are either produced via industrial process such as Haber-Bosch, or are mined with the aid of industrial machines). Industrialization also enables sedentary lifestyles since humans are now examining computer screens and sheets of paper, and riding in steel vehicles on paved roads and rails, rather than labouring.

I have examined the author's claims concerning altitude. He presents a coloured map of the United States and makes the claim

`Obesity is less common at high altitudes because of the watershed.`

Yet his coloured map shows California (Most of the population lives near sea level. Even inland Sacramento sits at 46 feet.) as substantially less obese than the Appalachian states. His hypothesis is interesting but the evidence appears lacking.

[simiones]

People with sedentary lifestyles were common in the 1900s as well, well above the 1% of the population that suffered from obesity. People with sedentary lifestyles have also tended to have more access to food, again with no corresponding explosion in obesity.

Also, agricultural output is not directly related to human consumption, past some base. So again, there may be second order effects on known causes of obesity (food and exercise) but if those are already controlled for, we are only left with unknown factors.

Regarding altitude, they do mention in a future article that California seems to be an exception, but that may be explained by California's drinking water being in a separate watershed than surrounding states. I don't know enough geography to know if this is accurate or not.

Edit: here is the quote from III:

> It’s important to note that altitude itself doesn’t affect obesity directly. Instead, altitude is a proxy for how high an area is in the watershed, which is itself a proxy for how badly the local water supply is contaminated. This is why Mississippi is more obese than low-lying areas of California. In California the water supply hasn’t traveled nearly as far in its path to the ocean, and has traveled past fewer farms, highways, cities, and factories.

[three14]

I'm curious if there's good data on what constitutes a "sedentary lifestyle" over time. In the early 1900s, I suspect people with desk jobs had a lot of small activity over the course of the day that we can now avoid. I take an elevator, drive for errands, and look up just about anything without leaving my desk. I don't even have to cross the room to turn on the modern equivalent of the radio. I don't have to get anything from a filing cabinet except for perhaps a few times a year. Is that the same as "sedentary" of old?

[simiones]

That's an interesting observation and you may well be right that people in the past were more active in this way.

On the other hand, the contribution small levels of exercise (such as getting up from your desk and walking at a normal pace, even climbing a few flights of stairs a couple of times per day) to calorie consumption is likely to be almost nothing - a few dozens of kcal over the course of a day at best. I know that there have been studies for example of the additional kcal consumption from a standing desk compared to a normal desk, and the result is almost non-existent, less than 10 kcal over the course of a workday.

[three14]

The question is whether the small-scale activity has an impact on hunger, though. Very anecdotally, when I'm active, I have an easier time feeling full.

[i_am_proteus]

>Also, agricultural output is not directly related to human consumption, past some base.

Precisely. Prior to the widespread industrialization of United States farms, there were occasional famines in the United States. 1/3 to 1/2 of the country lived on farms and were engaged in farming. The industrial revolution freed us from the burden of physical labor, and provided plentiful food.

If California an exception, are Washington and Oregon also exceptions? Why does obesity not increase as one travels down the Mississippi? One would expect Louisiana (Mississippi delta) to be substantially worse than Kentucky (more mountainous and well-upstream of Louisiana) and Michigan (situated on the Great Lakes). Michigan and Louisiana are similar, and Kentucky is much worse. I refer to the author's data source.[0]

[0]https://www.cdc.gov/obesity/data/prevalence-maps.html#states

[simiones]

> The industrial revolution freed us from the burden of physical labor, and provided plentiful food.

Sure, but that happened well before WWII, while the obesity epidemic started sometime around 1970-1980 and is growing rapidly. The vast majority of the US population in 1950-60 had all the food that they could possibly want, and yet <1% of them were obese, versus 30% percent today.

> One would expect Louisiana (Mississippi delta) to be substantially worse than Kentucky (more mountainous and well-upstream of Louisiana) and Michigan (situated on the Great Lakes). Michigan and Louisiana are similar, and Kentucky is much worse.

I don't know enough US geography to be able to sustain this point one way or another. I will just mention that the CDC data is not the only piece of data the article uses to show this correlation between altitude and BMI, but leave it at that.

[i_am_proteus]

>Sure, but that happened well before WWII, while the obesity epidemic started sometime around 1970-1980

This is not correct. Mass-scale industrialization of US farms didn't start happening until the 1930s. Remember that it was the internal-combustion engine (not the steam engine) that permitted the use of tractors and other machinery to supplant human and animal labor.

Now consider that it takes time for humans to become obese. The children raised during the beginning of the massive agricultural surplus were precisely the ones who were fueling the start of the epidemic in the 1970s.

[yorwba]

> people are exercising on average more today than in 2010 or 1990, and more than office workers in 1950, and still obesity is going up

SMTM's source [1] shows that "Percentage of adults aged 18 and over who met 2008 federal physical activity guidelines for aerobic activity through leisure-time aerobic activity" increased from slightly less than 45% in 1997 to slightly less than 55% in 2017. (I did not see a source for office workers in 1950.) But what really matters is the total physical activity. I'd be highly surprised if the increase in leisure-time exercise compensates for the decrease in jobs that require physical exertion for eight hours a day, every day.

[1] https://www.cdc.gov/nchs/data/nhis/earlyrelease/EarlyRelease... "Leisure-time physical activity" starts on page 43.

[giantg2]

"office workers in 1950"

What percentage of people filled that role then vs now and how does that compare to obesity rates? I assume both percentages were much lower in the 50s. Not to mention, many of the tasks that are automated today (or don't exist at all) were manual tasks back then. So they may not have been exercising explicitly, but it's likely their chores required manual activity that would qualify as low or medium intensity exercise... except maybe the richest ones that had servants of some sort do it for them.

[hellbannedguy]

And many were smokers.

[ginko]

Ooh, that's an interesting correlation. The number of smokers dropped a lot since the 80s, essentially right when the obesity epidemic started:

https://ourworldindata.org/smoking#the-rise-and-fall-of-smok...

Nicotine is known to suppress hunger

[giantg2]

It's also possible that nicotine triggers epigenetic changes that affect the metabolisms of future generations.

[irthomasthomas]

I agree with you on the first point, however, the sedentary lifestyle hypothesis is also out. It's part of the same f Fat Lazy Slob theory that always blames the people for their lifestyle choices. What do they tell you to do build up an appetite? Exercise. Exercise makes you hungry, and if you try to cure that hunger with low nutrient carbs then you will end up obese and malnourished.

[bsk26]

Looking back at the the first article in the series, they use hunter gatherer groups as examples of people who aren’t obese without acknowledging this is almost certainly due to extreme calorie restriction. Overeating might not explain everything but starving will definitely make you skinny