Many people claim, when they choose something that maps to conventional social values, that it's their personal decision and conventional social values have little or nothing to do with it.
I apply a simple test for that. I believe that it's possible for something to be really a personal decision not intensely influenced by conventional social values when there's actually some variety in people's choices around the issue.
So for example I believe "I want to be monogamous" or "I want to be polyamorous" can be a personal decision, because I know people who think both ways. I believe "I want shorter hair" and "I want longer hair" can be a personal decision because I know people who want both.
But I almost never see people saying "I want to gain some weight" or "I like that my weight fluctuates." I only ever hear people say "I want to lose some weight" or "I hate that my weight isn't stable." Even the majority of the people I've spoken to about this who are in the fat-acceptance communities (myself included) would prefer to lose some weight, although they might not want to be actually thin, and although they may not make any actual attempts to lose weight.
So, based on my current anecdotal evidence, desires about weight fail my test for being personal decisions not influenced by social values.
I don't think it's horrible that people are influenced by social values around this (except insofar as such influences causes them to do things that are harmful to themselves or others). But I really wish more people were aware of and/or willing to admit the influence.
Note: I'm including the following notions in "conventional social values": being moderately fat is automatically unhealthy, a moderately fat person's losing weight improves their health in the long term, and weight loss per se (rather than exercise) is the best way to improve health problems correlated to fatness. In my opinion those beliefs are social values rather than facts or firmly supported theories because they aren't well substantiated scientifically. If asked, I'll provide some references to back up my opinion about this, but I'm not interested in debating it, nor in other people debating it among themselves in my journal.