Gina Kolata describes an experiment by Ethan Sims in her book Rethinking Thin, where Sims put thin people on a forced-eating diet. Sims wanted to know whether people “would have a hard time gaining weight.” Kolata’s description of Sims’ and other similar experiments (such as putting people on starvation diets) plays a central role in establishing one of her main points—obesity is a biological problem.

In his first experiment with college students, Sims found that “these subjects found it all but impossible to gain much weight; no matter how much they tried to eat, they just could not become obese.” Sims reasoned that perhaps the students raised their activity levels and were burning off more calories. “He thought of the perfect subjects, people who really have no chance to cheat and burn off calories: prisoners.”

The study volunteers in prison did indeed gain weight. “But producing obesity turned out to be much harder than Sims had anticipated. The men increased their weight by 20 to 25 percent, but it took four to six months for them to do this, eating as much as they could every day. Some ended up eating 10,000 calorie a day, an amount so incredible that it would be hard to believe, were it not for the fact that the researcher study had attendants present at each meal who dutifully recorded everything the men ate.”

In this and other similar experiments, Sims showed that men gained weight at different rates, that metabolism rates change, and together these play a central role in the biological differences between naturally fat versus thin people. As Kolata writes, “The implications were clear. There is a reason that fat people can’t stay thin after they diet and that thin people can’t stay fat when they force themselves to gain weight. The body’s metabolism speeds up or slows down to keep weight within a narrow range.”

Having established this point, Kolata then turns to the genetics. But not before she writes, with a well-placed rhetorical flourish, “When the study ended, the prisoners had no trouble losing weight; within months, they were back to normal and effortlessly stayed there.”

I certainly bought into it. It’s only recently that I have begun to think whether these experiments tell us as much as they seem to do. I have already discussed a couple potential problems: a homeostasis versus a canalization model and the genetics as pointing to appetite as a central problem, not energy regulation.

But not the experiment itself—it was still framed by “no trouble” and “normal” and “effortlessly,” thin people as natural as can be.

Then I remembered Greg’s post on Exercise Is Mindset as well as Activity, where he described research that showed the hotel maids told that their work counted as exercise lost weight (with no accompanying change in activity level). Those that were not told effortlessly maintained their weight.

So, did the experiment determine the results in Sims’ work? I wouldn’t go that far. But presenting these experiments as an unproblematic view on our “natural” selves, yeah, that is a problem.

Why? For two reasons. First, all the research subjects were aware that it was an experiment, not real life. It was not something they would naturally do. And they must have remembered their original weight, which they surely considered their “normal” weight. So it wasn’t just the scientists framing the experiment, it was the research subjects.

Second, most weight gain does not happen this way in the real world. People do not set out consciously to gain weight. Weight gain happens insidiously, either slowly over time or occasionally in one big burst, when stress and fast food and having too much on your plate in every sense of the word all add up.

What do I think now? That the experiments tell us a lot about how people vary in their reactions to effortful weight gain. They tell us about people in that particular setting.

But I am no longer buying into the overarching science model both Kolata and Sims use, that the experiments tell us what we need to know about things in the “natural” world. I got snookered by my own expectations and assumptions, ingrained by fifth grade science experiments and tenth grade science papers.

But isn’t that the point of anthropology? Naïve assumptions get to us. So we need to go through the trouble and effort of examining ourselves as well as others. It is the philosopher’s stance, updated to the modern world, framed at once by the importance of data and the realization that the world does not revolve around us but the other way around.