A few weeks ago, the incredible Screaming Fat Girl linked to this film, A Matter of Fat, a 1970 National Film Board of Canada documentary on overweight and one man's last-ditch attempt to win his own personal war against the battle of the (very obese) bulge.
The movie lasts over 1 1/2 hours. It's worth the watch, but be prepared to set aside a good chunk of time to do so.
(Just as an aside, you may recognize the narrator's voice if you are of a certain age. It's Lorne Greene, or "Pa Cartwright" from Bonanza, as a generation of Canadians and Americans came to know him.)
There are a number of interesting themes to discuss in this movie and I highly recommend you watch it, but there's one interesting part that I'd like to discuss here: "fat" tastebuds, or, as the narrator described it in the film, "the faulty thermostat".
The documentary includes a description of several fascinating experiments. In the first, researchers observed that normal weight people reported that they were hungry when they had stomach contractions (as measured by a machine)--the body's signal to eat. They reported not being hungry when such contractions were absent. Not surprisingly, overweight people reported being hungry, even when there were no stomach contractions. But what is most interesting is that they sometimes reported not being hungry when they were having stomach contractions, the normal, physiological sign of hunger. Their ability to read their own physiological hunger signals was distorted.
In a second experiment, the subject was put in a room and asked to fill out a questionnaire that had nothing to do with weight or weight loss. He or she was also provided with a plateful of sandwiches. There was a clock in the room, which was rigged to go faster than normal. When the doctored clock showed 6 p.m. (it was actually around 5:20 p.m.), the time when many North Americans eat supper, the people of normal weight ate sparingly, since their bodies were (rightly) telling them that they weren't really all that hungry. The overweight subjects, on the other hand, saw the clock and started eating--and eating with gusto. An external signal was overriding (or outweighing, if you'll pardon the pun) the body's physiological signal. As the doctor describing the experiment said, obese people were "at the mercy of their environment." While individuals of normal weight listened to their "internal" (or physiological) cues, the overweight were influenced by "external" cues.
In a third experiment, subjects were asked to drink a bland liquid in place of eating actual food. They could drink as much of this liquid as they desired. When the experimenters measured the amount of liquid ingested, they observed that people of normal weight consumed the number of calories their bodies needed--no more and no less. The overweight subjects, on the other hand, markedly reduced their caloric intake--the food wasn't interesting so they ate less.
I find these three experiments to be fascinating and they go a long way towards describing my own relationship to food. As I have said before, I'm not an emotional eater. In fact, I find that more and more often, when I am emotionally distressed I am unable to eat, no matter what my stomach is telling me. I feel the hunger pangs but cannot, for emotional reasons, respond to them.
However, I love food. I recognize that I have to make a conscious effort to hold myself back from eating attractive foods just because they're there, even if I am not hungry. My eyes and my tastebuds scream "yes" while my stomach quietly (much too quietly) says "no". I find it hard to leave food on my plate. It's not the old "kids are starving in Africa" guilt kicking in. It's just that a lovely morsel beckons and I succumb to an external cue.
So "eat when you're hungry and stop when you're full"--the Paul McKenna mantra--really holds true. McKenna encourages us to eat like naturally thin people who eat when and what they like, but only when they're (GASP!!) hungry.