Previous entry here.

Where we left off, we were still in the process of looking at the deductive side of SMTM’s arguments; that is, where they1 are reinforcing the strength of their eventual argument by trying to show other possible explanations for the obesity epidemic are unworkable.

One way to quickly summarize the last article is to say that they are over-zealous in how they try to do this. My overall impression so far is that they are biased towards believing anything that potentially removes voluntary-in-any-sense behavior from the equation, such as here:

This perspective assumes that the body stores every extra calorie you eat as body fat, and that it doesn’t have any tools for using more or less energy as the need arises. But this isn’t the case. Your body has the ability to regulate things like its temperature, and it has similar tools to regulate body fatness. When we look closely, it turns out that “calories in, calories out” doesn’t match the actual facts of consumption and weight gain.
“This model seems to exist mostly to make lean people feel smug,” writes Stephen Guyenet, “since it attributes their leanness entirely to wise voluntary decisions and a strong character. I think at this point, few people in the research world believe the CICO model.”
It’s not that calories don’t matter at all. People who are on a starvation diet of 400 calories per day will lose weight, and as we will see in this section, people who eat hundreds of calories more than they need will usually gain weight. The problem is that this ignores how the body accounts for the calories coming in and going out. If you don’t eat enough, your body finds ways to burn fewer calories. If you eat too much, your body doesn’t store all of the excess as fat, and compensates by making you less hungry later on. Calories are involved in the math but it’s not as simple as “weight gain = calories in – calories out”.

Here we can see both characteristics of their anti-CICO arguing: they believe there’s a strong moral reason to reject CICO (regardless of its factual accuracy), and they are willing to reject it for any reason, here using a couple relatively old, relatively low-quality studies to prove more than they prove even if you disregard their iffyness:

The overfeeding studies also provide strong evidence against this hypothesis, since they find that it is hard for most people to gain weight and easy for them to go back exactly to the weight they were before the overfeeding. We think this leaves “willpower” explanations dead in the water. Most skinny people have no trouble staying that way.

Bolds mine. Similarly, they absolutely accept “set points” (the idea that your body chooses a weight then can and does do whatever it needs to stay at that point) as gospel truth. As far as I’ve deep-read so far, they don’t offer much supporting evidence that set points consistently exist and are powerful enough to cause the effects they attribute to them. Their statements regarding set points tend to be strong:

The lipostat explains why diet and exercise work a little, why they don’t work well enough to reverse obesity, and why even people who lose weight on diets generally end up gaining that weight right back.

You may say, “but if you eat less at a higher weight you will dip into fat stores to make up the difference”. Not if your set point is too high you won’t! If you eat less than you need and your body wants to defend your current weight, you will crave food and feel tired and stupid. Sound familiar?

I think that most people will find these statements seem intuitively true or false in conjunction with how much they accept “diets don’t work” as a truth. SMTM looks at a history of studies where doctors commanded people to diet, finds that people mostly didn’t lose weight or didn’t lose it long-term, and concludes that diets can’t and won’t work in an absolute sense - i.e., that even if you go on a calorie-reducing diet and actually maintain it that you won’t lose weight.

Other people (me included) don’t trust that rationale as much. Most diet studies take groups of people who know what dieting is and are overweight anyway; these are groups with a tautological history of failing to diet (Read: people who are overweight enough to have made it to a weight-loss study) and simply tell them to diet again; when they fail at this, it’s not surprising and doesn’t tell us that much.

That’s where we left off. From here, SMTM gets into examining particular types of diets, attempting to show that statements like “we are fat because we eat too much X now” are false. Since these affect the strength of SMTM’s eventual hypothesis, we have to examine their arguments related to those as well before we can move on.

Fair warning: I tend to agree with SMTM that where you get your calories doesn’t matter as much as some think it does, and as a result I care about his arguments here a lot less. Caveat emptor; I’m more likely to be lazy here.

Fat

When you are trying to find groups of people who consistently subsist on one outlier food, you are pretty much forced to go find some weird tribe in the middle of nowhere who eats huge amounts of that food due to either a weird culture or poor variety in the foods available to them. SMTM does this over and over, but always in a way you could describe as biased, simplistic, or dishonest (take your pick). In the case of fat, they say this:

Plenty of cultures eat extremely high-fat diets and remain very lean indeed. You’ll remember that the Maasai diet is about 3000 calories per day, and 66% of that is from fat. But the Maasai don’t suﬀer from obesity. In fact, Kalahari Bushmen love fat and apparently wax poetic about it.

If you have a suspicious mind, this kind of statement is really, really weird in isolation. The reason why is that we would expect the life of a Bushman to be different from ours in dozens of big ways. Bushmen presumably don’t have the same level of access to Hulu as we do, for example; presumably, the “marketplace” of free-time-expenditure choices a Bushman has access to looks a lot different than ours.

So we shouldn’t be surprised when we follow the link that SMTM provided and find the bolded statements below:

“My friend, the way it is with us Bushmen,” he began, “is that we love meat. And even more than that, we love fat.”
In the afternoon it was Tomazo’s turn. Tomazo is a fine hunter, a top trance performer, and one of my most reliable informants. He approached the subject of the Christmas cow as part of my continuing Bushmen education.
“My friend, the way it is with us Bushmen,” he began, “is that we love meat. And even more than that, we love fat. When we hunt we always search for the fat ones, the ones dripping with layers of white fat: fat that turns into a clear, thick oil in the cooking pot, fat that slides down your gullet, fills your stomach and gives you a roaring diarrhea,” he rhapsodized.

This is a big thing to ignore, but ignore it SMTM does. A third of the calories these people bring in are from food they hunt and butcher themselves. This is a community where there’s one source of water that people might be walking a mile to get to:

A borehole well with its diesel pump and water tower served the entire community; the hand-dug wells had fallen into disuse.

So yes, these people eat a lot of fat and yet remain slim. But while I can’t say for sure that I’d stay slim if I had to personally hunt, kill and butcher 33% of the calories I eat, it’s a big enough confounder that it needs to be mentioned. SMTM does not mention it.

They then move on to link to this review noting that the fat content of a diet doesn’t seem to make a big difference in how much weight loss people experience and maintain. But again, both SMTM and I would expect that - it doesn’t reinforce their point so much unless you assume their “dieting is literally impossible even if you stick to it” set-point prior is true.

They again ignore the obvious questions here:

This is a little diﬃcult to square with animal studies that find that a high-fat diet reliably leads to obesity in monkeys, dogs, pigs, hamsters, squirrels, rats, and mice. It could just be that humans are not monkeys, dogs, pigs, hamsters, squirrels, rats, or mice, and that while dietary fat has an adverse effect on these species, it doesn’t do much to us. Some of the hamster studies, for example, induced obesity simply by giving the hamsters extra sunflower seeds, a phenomenon not observed in humans. Pigs, in particular, will become obese even on low-fat diets when given the opportunity.
We even see differences within a specific kind of animal. The same high-fat diet will make one species of hamster (Syrian hamsters) obese and leave another species of hamster (golden hamsters) merely chubby. If the findings can’t generalize between different species of hamsters, we shouldn’t expect them to generalize to humans.
It could also be that dietary fat leads to obesity in mammals held in captivity, possibly due to factors like stress. Metabolic ward studies restrict your movement, but it’s not exactly like living your whole life in a laboratory cage. And it’s worth noting that about 10–15% of macaque and rhesus monkeys in captivity become obese when they reach middle age, despite the fact that they are fed a relatively low-fat (10% of energy) diet.

I want you to imagine that you are writing an article about obesity, and you’ve dug so deep into it that you know about potential differences in diet composition in different kinds of hamsters. Get into that mindset. Imagine the amount of work, but also imagine how much thought you’ve had to put into this - how much time your mind has had to examine the nooks and crannies of the issue.

Now imagine that you write three paragraphs trying to resolve an apparent conflict where most animals get fat on a high-fat diet but you can’t necessarily see that same relationship in humans. You are digging deep, looking at all the reasons, trying to look reasonable to your audience, etc.

Now imagine that you’ve done all this, and you decide not to note that one of the big differences between humans and animals in captivity is animals in captivity have no say in what they eat, and thus can be relied on to reliably follow a diet in terms of the composition of what they eat, as opposed to humans where that’s not the case. You also choose to not note that honesty/reporting accuracy are also factored out, since their food intake can be monitored by outside observers.

I know that’s a lot of italics, but they do this with everything and it’s exhausting. Where a question doesn’t seem like it will reinforce his point, they just don’t ask the question.

Anyway, fat is a bust. We learn nothing new.

Carbs

SMTM says the following is all you need to know about carbs, and I tend to agree with them:

Ok, maybe fat doesn’t make you fat. How about carbohydrates? All this bread can’t be good for us.
This theory is dead on the starting line, though, because as obesity has gone up, consumption of carbohydrates has gone down (see figure).

SMTM includes a Guyenet-provided chart they had permission to use (but I don’t have permission to use, and thus goes unseen here) showing that USDA/CDC estimates indicate Americans overall are eating fewer carbs since 2000-ish. I could nitpick and say that this doesn’t tell us absolutely everything we’d want to know about how carb-consumption is distributed at an individual level, but I’m not sure it matters in the first place so I’m not going to.

The differences are also pretty small (~530g a day in 200 to about 480g now), but since carb intake in 1980 was only about 410g by the same estimates, the differences don’t really look big enough in general to be causing this. They could if things work in a really complex way we wouldn’t expect, but it’s very far from a smoking gun.

He also supplies this study:

609 people fed a whole-food, high-carbohydrate diet lost 12 pounds (5.3 kg) over one year, not significantly different from the 13 pounds (6.0 kg) of weight lost on a whole-food low-carbohydrate diet.

Note that although SMTM says “fed”, the intervention was entirely advice-based; they didn’t provide food or monitor food intake in any way beyond questionnaires from what I can see in the study itself.

SMTM includes some more useless stuff about tribesmen, but then notes that Japanese people tend to gain weight when shifting from their diet to ours:

In fact, people who move from Japan to the US and begin eating less white rice become much heavier. This suggests that the diﬀerence isn’t simply genetic.

Since they are moving to a high-fat diet, this would at least be some evidence that fat was a problem here, but that wouldn’t indicate lithium as a cause so SMTM hand-waves it:

These immigrants do end up eating a diet much higher in fat — but of course, from the previous section, we’ve seen that fat can’t be responsible for this change.

And that’s about it. Again, I think I agree with SMTM here about food type not mattering that much regardless, but again they prove very little and we learn next to nothing (while, of course, being told we’ve learned everything).

Sugar

Basically ditto to carbs. SMTM notes that sugar consumption is mostly dropping but obesity keeps going up, which is still a decent point. They bring up a bunch of non-comparable tribesmen groups again, which is still dumb. But, wonder of wonders, SMTM has a metabolic ward study (read: one where the scientists actually studied what people ate, as opposed to telling them to eat less and acting shocked when they didn’t). It’s still not that helpful, but it’s better:

Design: Seventeen overweight or obese men were admitted to metabolic wards, where they consumed a high-carbohydrate baseline diet (BD) for 4 wk followed by 4 wk of an isocaloric KD with clamped protein. Subjects spent 2 consecutive days each week residing in metabolic chambers to measure changes in EE (EEchamber), sleeping EE (SEE), and RQ. Body composition changes were measured by dual-energy X-ray absorptiometry. Average EE during the final 2 wk of the BD and KD periods was measured by doubly labeled water (EEDLW).
Results: Subjects lost weight and body fat throughout the study corresponding to an overall negative energy balance of ∼300 kcal/d. Compared with BD, the KD coincided with increased EEchamber (57 ± 13 kcal/d, P = 0.0004) and SEE (89 ± 14 kcal/d, P < 0.0001) and decreased RQ (-0.111 ± 0.003, P < 0.0001). EEDLW increased by 151 ± 63 kcal/d (P = 0.03). Body fat loss slowed during the KD and coincided with increased protein utilization and loss of fat-free mass.

This wasn’t really a diet in the calorie reduction sense of the word - mostly the researchers were changing the composition of the diets to reduce carbs without reducing overall caloric intake and seeing if that made any significant difference. Their results were confusing (people lost weight during the baseline, no-change-from-normal-diet phase and the researchers didn’t know why) but didn’t indicate a huge difference in terms of how they reacted to a controlled, baseline “normal” diet compared to a low-carb-low-sugar diet at the same caloric value.

Again, we don’t learn a lot here. It’s very plausible that sugar isn’t causing the obesity epidemic, but there’s nothing shocking revealed here.

Various kinds of fad diets

I’m going to be very lazy and skip most of this section, but I have a reason:

You’ll recall that Mystery 8 is that all diets work about equally well. It doesn’t matter which diet you choose — you lose about the same number of pounds regardless.
All diets work. The problem is that none of them work very well. Stick to just about any diet for a couple weeks and you will probably lose about 10 pounds. This is ok, but it isn’t much comfort for someone who is 40 lbs overweight. And it isn’t commensurate with the size of the obesity epidemic.
Systematic comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates finds that across many different reduced-calorie diets, people lose about 13.2 lbs (6 kg) over six months, and that in all cases people began to gain weight back after 12 months. It’s not just weight loss, either. Satiety, hunger, satisfaction with the diet, and adherence to the protocol is similar for all diets.
There are too many diets to review in full, of course, but we see the same pattern in every diet that has been extensively studied. Let’s look at just a few.

SMTM looks at several diets and finds they mostly don’t work, but recall that they are refusing to consider the idea that people for the most part don’t follow diets based on the say-so of their doctors. So we are left in a limbo where SMTM is saying “diets don’t work because lithium”, but not acknowledging that in the vast majority of the sources SMTM provides there’s no way of knowing if the people dieted (or continued to diet) at all.

If they are right - if everyone just naturally “diets” and eats normal, healthy-weight-sustaining amounts of food in the absence of chemical contaminants - then the failure of most people to lose weight when assigned diets is not only shocking because of the failure, but shocking because people need a diet assigned at all.

If they are wrong - if people eat more than they used to or exercise less than they used to for reasons not related to lithium - then none of this is surprising at all.

Since SMTM’s prior of “this couldn’t possibly be anyone’s fault in any sense whatsoever, it can’t be related to food getting better or entertainment outweighing exercise or anything like that” is so strong, the article up to this point ends up reading a lot differently than I think they thought it would. I think all the evidence SMTM provides seems to them to very clearly indicate more than it actually does, both because it makes his eventual point more compelling and because it confirms a worldview SMTM says they are morally obligated to hold.

This was a short one, but now that we’ve more-or-less figured out that most other conventional explanations are still in play, we can look at SMTM’s actual ideas regarding chemical contaminants with a clean mental palate. Rejoice: the groundwork part is over, and the important part is coming soon.

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I said “he” in the last article referring to SMTM; apparently, they are a “they” in the literal sense where there’s more than one person writing these articles. I can not recall if I knew this or not, but I’ve been convinced to switch horses midstream on this one.

Resident Contrarian

Slowly Parsing SMTM's Lithium Obesity Thing…