I think this is where the book gets really interesting, as she's starting to make the argument that obese people are biologically different from the non-obese. Not psychologicallly different, but biologically.
So, here her point is that thin AND obese people eat from stress, suffer from depression at equal levels, etc. But only the obese ones gain weight from the behavior. I think she's saying that there IS an emotional component for obesity, in that we got fat because we overate, often for emotional reasons. But, her bigger point is that non-obese people engage in the same behaviors and just don't gain weight.
She also tries to make the point that it's not culture. Obese people and non-obese people are exposed to the same culture and yet the obese gain weight and the non-obese do not.
That is what I perceive her argument to be. I'm not sure what I make of it. I'm a cultural psychologist, and I would like to believe culture and environment are significant factors in all sorts of our attitudes and behaviors. In my work, I tend to ignore the biological to a degree. I think I carried this over to my thinking about weight and obesity.
Kolata raised a lot of points I hadn't really considered before -- and I think her argument is not really strong here. I don't know enough about the research to be convinced by it. Her argument seems much stronger in the later chapters dealing with the biochemistry of obesity.
My 5 C's of healthy living: Commitment to conscious control, with the understanding that choices have consequences