Lesley at Two Whole Cakes brought this article to my attention. In order to study obesity, some scientists are keeping monkeys–rhesus macaques–in individual cages to more easily monitor their food intake and to limit their exercise. These monkeys eat when they’re bored, similar to humans (and unlike rats), so limiting their exercise not only prevents them from burning calories, but also probably increases their food intake by making them even more bored, with not much to alleviate the boredom except food.
We could expect some problems with any obesity research coming from studies of these monkeys.
They are probably avoiding the biggest problems by comparing two different groups of obese monkeys rather than obese and normal-weight monkeys in the studies mentioned. (For example, “a group of academic researchers is using the monkeys to compare gastric bypass surgery with weight loss from forced dieting”.) Obviously, comparing these monkeys with a group of monkeys that live in groups, have unlimited access to exercise, and eat in “meals” instead of grazing all day, you’d expect to see some differences even if the two groups weighed the same.
Still, they are only studying monkeys who are fat because they sit around snacking all day–and probably partly due to stress as well–monkeys kept in individual cages are going to be stressed, period. They are not studying monkeys who are fat for any other reason. Their results may not apply to individuals who are not fat for that reason–people who are fat in spite of basically healthy eating and exercise habits. And the stress of isolation may have unpredictable effects on the outcome of the experiments. In the experiment where they compared monkeys on weight-loss diets with monkeys who have weight-loss surgery, would stress dampen the hormonal changes related to each of these treatments? Stress makes every disease worse, so in some ways it might make different treatments easier to study–more monkeys overall would be getting heart attacks during the follow-up period, etc.
I also notice that the article says, “Still, about 40 percent do not put on a lot of weight.” (No further explanation or discussion is given.) This is similar to the roughly one-third of Americans who are normal weight. Hm, maybe most thin people aren’t thin because of their virtuousness?