Critiquing Gary Taubes, Part 4: What Causes Obesity?

Pre­vi­ously: Main­stream Nutri­tion Science on Obe­sity, Atk­ins Re­dux, Did the US Govern­ment Give Us Ab­surd Ad­vice About Su­gar?

In this post, I’m go­ing to deal with an is­sue that’s cen­tral to Gary Taubes’ cri­tique of main­stream nu­tri­tion sci­ence: what causes obe­sity?

This is a post a post I found ex­cep­tion­ally difficult to write. You see, while his 2002 New York Times ar­ti­cle por­trays main­stream nu­tri­tion sci­ence as pro­mot­ing a sim­plis­tic mir­ror-image of the Atk­ins diet, his books do man­age to talk about the main­stream view that if you con­sume more calories than you burn you’ll gain weight… sort of. As I looked closely at the rele­vant chap­ters of those books, it be­came less and less clear what view he’s at­tribut­ing to main­stream ex­perts, or what his al­ter­na­tive is sup­posed to be.

Be­cause this dis­cus­sion may get con­fus­ing, I want to start by re­peat­ing what I said in my first post: the main­stream view is that peo­ple gain weight when they con­sume more calories than they burn, but both calorie in­take and calorie ex­pen­di­ture are reg­u­lated by com­pli­cated mechanisms we don’t fully un­der­stand yet.

Yet Taubes goes on at great length about how obe­sity has other causes be­yond sim­ple calorie math as if this were some­how a re­fu­ta­tion of main­stream nu­tri­tion sci­ence. So I’m go­ing to provide a se­ries of quotes from rele­vant sources to show that the ex­perts are perfectly aware of that fact. All of the fol­low­ing sources are ones Taubes cites as ex­am­ples of how ab­surd the views of main­stream nu­tri­tion ex­perts sup­pos­edly are:

The etiol­ogy of obe­sity is mul­ti­fac­to­rial and in­cludes ge­netic, neu­ro­hor­monal, en­docrine, metabolic and life-style-as­so­ci­ated fac­tors. Gen­er­ally, obe­sity is a re­sult of ex­cess en­ergy re­sult­ing from dis­tur­bances in the en­ergy in­take/​ex­pen­di­ture equil­ibrium.

Re­port From FDA’s Su­gars Task Force. 1986. p. S14.

The causes of obe­sity are in­com­pletely un­der­stood, so that effec­tive treat­ment is difficult. Obe­sity is the net re­sult of an ex­cess of en­ergy con­sump­tion over ex­pen­di­ture. Fac­tors that must be con­sid­ered as con­tribut­ing to cau­sa­tion are: (1) hered­ity, (2) pri­mary overeat­ing, (3) al­tered metabolism of adi­pose tis­sue, (4) defec­tive or de­creased ther­mo­ge­n­e­sis (the pro­cess by which calories are con­verted into heat), (5) de­creased phys­i­cal ac­tivity with­out an ap­pro­pri­ate re­duc­tion in food in­take, and (6) cer­tain pre­scribed med­i­ca­tions. Th­ese po­ten­tial causes can in­ter­act with one an­other. Of the six fac­tors, in­di­vi­d­u­als may have some con­trol of overeat­ing and un­der­ac­tivity.

The Sur­geon Gen­eral’s Re­port on Nutri­tion and Health. 1988. p. 290.

Pos­i­tive en­ergy bal­ance can re­sult from in­creased en­ergy in­take, re­duced en­ergy ex­pen­di­ture, or both, and over the long term, can lead to obe­sity and its as­so­ci­ated com­pli­ca­tions… Obe­sity is en­hanced not only by this en­ergy im­bal­ance but also by a ge­netic pre­dis­po­si­tion to obe­sity and al­tered metabolic effi­ciency… The spe­cific causes of obe­sity are not well known, al­though some obese peo­ple clearly con­sume more en­ergy com­pared to peo­ple of nor­mal weight, whereas oth­ers are very seden­tary or may have in­creased metabolic effi­ciency.

1989 Na­tional Academy of Sciences Diet and Health re­port. 1989. p. 10.

Main­te­nance of a nor­mal body weight re­quires a match of food in­take to en­ergy ex­pen­di­ture… Both nu­tri­ent in­take and en­ergy ex­pen­di­ture are reg­u­lated by a com­plex in­ter­ac­tion be­tween the periph­ery and the cen­tral ner­vous sys­tem. Although not all as­pects of cen­tral-periph­eral in­ter­ac­tions in­volved in en­ergy bal­ance are un­der­stood, key fac­tors have been iden­ti­fied. For ex­am­ple, lep­tin from the adipocyte, ghre­lin from the stom­ach, pep­tide YY from the gut, and in­sulin from the pan­creas are all in­volved in the cen­tral reg­u­la­tion of en­ergy bal­ance. In the brain, more than a dozen pep­tides have been im­pli­cated in ap­petite and satiety.

Ar­ti­cle on obe­sity on Joslin’s Di­a­betes Mel­li­tus. p. 536.

There’s also the Hand­book of Obe­sity (whose first edi­tion sadly does not ap­pear to be eas­ily ac­cessible on­line), which I at­tempt won’t quote from be­cause it de­votes dozens of chap­ters to the etiol­ogy of obe­sity, in­clud­ing chap­ters ti­tled “The Ge­net­ics of Hu­man Obe­sity,” “Be­hav­ioral Neu­ro­science of Obe­sity,” and “En­docrine Deter­mi­nates of Obe­sity.”

Now what ex­actly is Taubes’ ob­jec­tion to the above state­ments? It’s easy to find an­swers to this ques­tion in his books. It’s less easy to rec­on­cile all the differ­ent an­swers with each other. At times, he seems to sug­gest the above state­ments are self-con­tra­dic­tory, such as when he gives the fol­low­ing ex­am­ple of an “ap­par­ent con­tra­dic­tion” (in Good Calories, Bad Calories on p. 271):

It may be true that, “for the vast ma­jor­ity of in­di­vi­d­u­als, over­weight and obe­sity re­sult from ex­cess calorie con­sump­tion and/​or in­ad­e­quate phys­i­cal ac­tivity,” as the Sur­geon Gen­eral’s Office says, but it also seems that the ac­cu­mu­la­tion of fat on hu­mans and an­i­mals is de­ter­mined to a large ex­tent by fac­tors that have lit­tle to do with how much we eat or ex­er­cise, that it has a biologic com­po­nent.

At times like this, Taubes re­minds me of the biol­o­gists who Ernst Mayr chided in his pa­per “Cause and Effect in Biol­ogy” for failing to re­al­ize that biolog­i­cal phe­nomenon can be cause on mul­ti­ple lev­els. Mayr quotes an ex­am­ple:

The ear­lier writ­ers ex­plained the growth of the legs in the tad­pole of the frog or toad as a case of adap­ta­tion to life on land. We know through Gun­der­natsch that the growth of the legs can be pro­duced at any time even in the youngest tad­pole, which is un­able to live on land, by feed­ing the an­i­mal with the thy­roid gland.

Just as there’s no con­tra­dic­tion be­tween think­ing leg growth in tad­poles is con­trol­led by hor­mones, and think­ing this mechanism is an evolu­tion­ary adap­ta­tion, there’s no con­tra­dic­tion be­tween think­ing weight gain is the re­sult of con­sum­ing more calories than you burn, and also think­ing that there are a lot of differ­ent fac­tors that in­fluence calorie in­take and ex­pen­di­ture.

But maybe Taubes doesn’t mean to sug­gest there’s a con­tra­dic­tion there. He goes to great lengths to as­sure his read­ers he isn’t re­ject­ing the laws of ther­mo­dy­nam­ics. Fur­ther­more, he doesn’t seem in­ter­ested in claiming any loop­holes in the ba­sic calories-in, calories-out math along the lines of Atk­ins’ ke­tones-in-the-urine hy­poth­e­sis. In­stead, the idea of­ten seems to be that the calories-in, calories-out idea is true but triv­ial. Why We Get Fat (p. 74) offers this anal­ogy:

Imag­ine that, in­stead of talk­ing about why we get fat, we’re talk­ing about why a room gets crowded...

If you asked me this ques­tion and I said, Well, be­cause more peo­ple en­tered the room than left it, you’d prob­a­bly think I was be­ing a wise guy or an idiot. Of course more peo­ple en­tered than left, you’d say. That’s ob­vi­ous. But why?

This is a poor anal­ogy, be­cause the fact the im­por­tance of calories in weight gain is far less ob­vi­ous than the im­por­tance of peo­ple in a room’s get­ting crowded. Imag­ine: what if it had turned out that it’s the to­tal mass of your food that mat­ters? Or just the to­tal grams of fat? Or just the to­tal grams of carbs? Or the phlo­gis­ton con­tent?

A poorly-cho­sen anal­ogy, though, is a minor prob­lem com­pared to the false im­pli­ca­tion that main­stream that obe­sity re­searchers have ig­nored the fac­tors that in­fluence calorie in­take and ex­pen­di­ture. This is a claim that Taubes makes ex­plicit in other cases, for ex­am­ple:

Good Calories, Bad Calories (p. 295):

What may be the sin­gle most in­com­pre­hen­si­ble as­pect of the last half-cen­tury of obe­sity re­search is the failure of those in­volved to grasp the fact that both hunger and seden­tary be­hav­ior can be driven by a metabolic-hor­monal dis­po­si­tion to grow fat, just as a lack of hunger and the im­pulse to en­gage in phys­i­cal ac­tivity can be driven by a metabolic-hor­monal dis­po­si­tion to burn calories rather than store them.

Why We Get Fat (pp. 80-81):

Of all the dan­ger­ous ideas that health offi­cials could have em­braced while try­ing to un­der­stand why we get fat, they would have been hard-pressed to find one ul­ti­mately more dam­ag­ing that calories-in/​calories-out… it’s mis­lead­ing and mis­con­ceived on so many lev­els that it’s hard to imag­ine how it sur­vived un­scathed and vir­tu­ally un­challenged for the last fifty years...

There has to be a rea­son, of course, why any­one would eat more calories than he or she ex­pends, par­tic­u­larly since the penalty for do­ing so is to suffer the phys­i­cal and emo­tional cru­elties of obe­sity. There must be a defect in­volved some­where; the ques­tion is where.

The logic of calories-in/​calories-out al­lows only one ac­cept­able an­swer to this ques­tion. The defect can­not lie in the body-per­haps, as the en­docri­nol­o­gist Ed­win Ast­wood sug­gested half a cen­tury ago, in the “dozens of en­zymes” and the “va­ri­ety of hor­mones” that con­trol how our bod­ies “turn what is eaten into fat”—be­cause this would im­ply that some­thing other than overeat­ing was fun­da­men­tally re­spon­si­ble for mak­ing us fat. And that’s not al­lowed. So the prob­lem must lie in the brain. And, more pre­cisely, in be­hav­ior, which makes it an is­sue of char­ac­ter.

To which I re­ply: no, those in­volved in obe­sity re­search did not fail to grasp the fac­tors that drive hunger and seden­tary be­hav­ior, and there was no un­challenged dogma the causes of obe­sity can’t lie in our bod­ies. Read your own damn sources, Taubes.

I wish I could end this post there, but there’s a com­pli­ca­tion: what about those state­ments I talked about in part 2, that it’s “not a med­i­cal fact” that los­ing weight re­quires cut­ting down on ex­cess calories, and that dietary fat has no effect on fat ac­cu­mu­la­tion in the body? Well, there is an ex­pla­na­tion for those state­ments. It’s some­thing Taubes goes on at great length about in Good Calories, Bad Calories, but is per­haps most suc­cinctly ex­pressed in Why We Get Fat (p. 99): “We don’t get fat be­cause we overeat; we overeat be­cause we’re get­ting fat.”

The part of me that’s still try­ing to figure out how to be char­i­ta­ble to Taubes urges that surely that sen­tence wasn’t meant to be taken too liter­ally. To use Taubes’ own anal­ogy of the room get­ting crowded: it’s one thing to say “the room is get­ting crowded be­cause more peo­ple are en­ter­ing than leav­ing” is too ob­vi­ous to men­tion. It’s an­other thing to say that that claim is false, and on the con­trary it’s the room get­ting crowded that’s caus­ing peo­ple to en­ter. (There’s a sense in which that could be true given the phe­nomenon of so­cial proof, but then we’re talk­ing about a feed­back loop, not one-way cau­sa­tion.)

So it’s nat­u­ral to as­sume Taubes is play­ing with mean­ing here a bit, us­ing “get­ting fat” to re­fer not to the weight gain it­self but a metabolic ten­dency to get fat, or some­thing like that. Surely he still rec­og­nizes that how much we eat still has an effect on our weight, right? On the one hand it seems that he does: he talks about how calorie in­take af­fects calorie ex­pen­di­ture, but he doesn’t claim they march so closely in lock­step that it’s liter­ally im­pos­si­ble to lose weight by cut­ting calorie in­take. His dis­cus­sion of low-calorie diets plays up how un­pleas­ant they are, but he does ac­knowl­edge peo­ple lose weight on them.

On the other hand… Taubes seems re­ally se­ri­ous about this claim, por­tray­ing it as one of the fun­da­men­tal mis­takes of main­stream nu­tri­tion ex­perts. From Good Calories, Bad Calories (p. 293):

The first law of ther­mo­dy­nam­ics dic­tates that weight gain—the in­crease in en­ergy stored as fat and lean-tis­sue mass—wil be ac­com­panied by or as­so­ci­ated with pos­i­tive en­ergy bal­ance, but it does not say that it is caused by a pos­i­tive en­ergy bal­ance—by “a plethora of calories,” as Rus­sel Ce­cil and Robert Loeb’s 1951 Text­book of Medicine put it. There is no ar­row of causal­ity in the equa­tion. It is equally pos­si­ble, with­out vi­o­lat­ing this fun­da­men­tal truth, for a change in en­ergy stores, the left side of the above equa­tion, to be the driv­ing force in cause and effect; some reg­u­la­tory phe­nomenon could drive us to gain weight, which would in turn cause a pos­i­tive en­ergy bal­ance—and thus overeat­ing and/​or seden­tary be­hav­ior. Either way, the calories in wil equal the calories out, as they must, but what is cause in one case is effect in the other.

All those who have in­sisted (and still do) that overeat­ing and/​or seden­tary be­hav­ior must be the cause of obe­sity have done so on the ba­sis of this same fun­da­men­tal er­ror: they will ob­serve cor­rectly that pos­i­tive caloric bal­ance must be as­so­ci­ated with weight gain, but then they will as­sume with­out jus­tifi­ca­tion that pos­i­tive caloric bal­ance is the cause of weight gain. This sim­ple mis­con­cep­tion has led to a cen­tury of mis­guided obe­sity re­search.

He even goes so far as to say (in Why We Get Fat, p. 76):

The ex­perts who say that we get fat be­cause we overeat or we get fat as a re­sult of overeat­ing—the vast ma­jor­ity—are mak­ing the kind of mis­take that would (or at least should) earn a failing grade in a high-school sci­ence class.

So what’s go­ing on here? I think the an­swer lies Taubes’ ea­ger­ness to por­tray main­stream nu­tri­tion ex­perts as big mea­nies who blame fat peo­ple for be­ing fat. I’ve already quoted him as say­ing that on the main­stream view, be­ing over­weight or obese must re­sult from a defect of char­ac­ter. Just to drive the point home, in the same book he later says (p. 84):

Much of the last half-cen­tury of pro­fes­sional dis­course on obe­sity can be per­ceived as at­tempts to cir­cum­vent what we could call the “head case” im­pli­ca­tions of calories-in/​calories-out: how to blame obe­sity on eat­ing too much with­out ac­tu­ally blam­ing the fat per­son for the hu­man weak­nesses of self-in­dul­gence and/​or ig­no­rance.

So if you hear an ad­vo­cate of the main­stream view claiming not to be a big meanie, don’t be­lieve them!

But this puts Taubes in a bind: now if he says how much we eat has an effect on our weight, he’s a big meanie too. It doesn’t work for him to say fat peo­ple can’t help overeat­ing be­cause of some­thing wrong with their metabolism, and this in turn causes them to gain weight, be­cause he’s com­mit­ted him­self to the prin­ci­ple that blam­ing be­hav­ior equals blam­ing a char­ac­ter defect. So in­stead, we get wild rhetoric about how stupid the ex­perts are with no co­her­ent view un­der­neath it.

A more sen­si­ble ap­proach would’ve been to em­pha­size that akra­sia is an ex­tremely com­mon prob­lem for hu­mans, and that peo­ple who don’t suffer from akra­sia in re­gards to diet prob­a­bly suffer from akra­sia about some­thing else. But that wouldn’t have made for as an ex­cit­ing of a book. Robin Han­son once com­mented that “few folks ac­tu­ally care much about the fu­ture ex­cept as a place to tell moral­ity tales about who to­day is naughty vs. nice.” I sus­pect this point gen­er­al­izes. If you want to sell a book, flat­ter your au­di­ence and give them some villains to hate.

I have no plans of dis­cussing Taubes claims about car­bo­hy­drates hav­ing a unique abil­ity to mess up the sys­tems that reg­u­late weight. For one thing, I don’t have any­thing to add to what oth­ers have already said. For an­other, one thing Taubes is definitely not claiming is, “while obe­sity re­searchers have spent a great deal of time study­ing the mechanisms that reg­u­late weight, they’ve com­pletely failed to re­al­ize how badly carbs screw up these mechanisms.”

In­stead, he ac­cuses them of ig­nor­ing the rele­vant mechanisms en­tirely. This claim is so wildly un­true as to be grounds to doubt any­thing you think you learned from Taubes—in­deed, to doubt any ideas you origi­nally got from him even if you thought you later got con­fir­ma­tion for them el­se­where.

Clos­ing thought: it’s quite pos­si­ble for a ma­jor­ity of the ex­perts to be wrong. And I can even imag­ine find­ing a case some­where where a non-ex­pert ra­tio­nally ar­rived at the cor­rect an­swer when 95% of the ex­perts are wrong—though I’ve been un­able to ac­tu­ally find such a case. But when you see some­one claiming that the vast ma­jor­ity of the ex­perts have an ob­vi­ously stupid view that should have earned them a failing grade in high school sci­ence, that is a very strong sig­nal that you are deal­ing with a crack­pot.