When people are asked why they want to or are trying to lose weight, these are the two most common reasons:
1) They want to improve their health.
2) They want to improve their looks.
Now, there are some health issues (knee problems, for example) for which weight loss can really help, and many (though not all) habits which lead to long-term weight loss also improve health. But there are far easier ways to address most health issues than weight loss, and I think the rational approach would be to try those things before trying weight loss.
As far as improving looks … judgement of looks is more subjective than judgement of health, and we live in a society which says thin people look better. Nonetheless, I think even in a fat-phobic society there are far easier ways to ‘improve’ one’s looks than weight-loss (learning how to pick out good clothes, learning how to use make-up well, etc).
I think, however, that these are the REAL reasons most people want to lose weight:
1) Social compliance
2) Bodily control
In a fat-phobic society – and I would say both the United States and Taiwan are fat-phobic – people are pressured into losing weight in order to conform to social norms. I don’t think there is any rational reason for a society to impose this on people, and I am fat-positive in the sense that I don’t think people should be judged based on their weight.
But I think the deeper reason is a wish to have control over one’s bodies. For example, it is noted that rape victims often get eating disorders, and most analyses I’ve read say this is a way for them to reassert control over their bodies. Those are extreme cases, but I think even a simple wish to lose weight is often a wish to have more control over one’s body.
Of course, weight loss does not always demonstrate control over one’s body. Sometimes, it demonstrates the opposite. As I’ve experienced.
After moving to Taiwan, I started losing a significant amount of weight. It did not happen too quickly, but over the months it added up. Many people might think that was wonderful … but it scared me. I was not trying to lose weight. I was worried that maybe I got a parasite, or there was something wrong with the food, or that there was some lurking health problem.
Since then, my weight has stabilized, and doctors haven’t noted anything unusual about my body. So now, I think it was just the effect of a lifestyle change (and hey, maybe I’ll get the weight back when I return to the United States). But the experience did help me appreciate how much of the psychology of weight change is motivated by a desire for bodily control … and how unintentionally changing weight makes me feel that I can’t control my body.