Is thinshaming actually the norm? I'd say it's certainly something that's a problem (any kind of bodyshaming is, really), but I'm not sure that it's more common than fatshaming. And I think the pushback against the latter, as well as the apparent growing acceptance of being overweight, has more to do with a greater number of people being overweight and less to do with the ability of people to resist certain messages. The rise in obesity rates doesn't necessarily track to people no longer valuing a certain body type.
All of that said, around half (and I recall coming across a study that found the number to be upwards of 60%. Most of what I've seen tends toward the lower figure, though, so I'm going with that) of elementary-aged girls report concerns over their weight and body type (namely, that they're "too fat"), and compare themselves unfavorably to the women they see in magazines and on TV/in movies. The cycle of dieting starts with girls as young as age 9. Also, since the late aughts, the prevalence of eating disorders in teenage girls has increased. Despite what may be some trends in the right direction, girls are receiving a certain set of messages about how they should look, and many of them are taking it to heart.
Re: Actually..
All of that said, around half (and I recall coming across a study that found the number to be upwards of 60%. Most of what I've seen tends toward the lower figure, though, so I'm going with that) of elementary-aged girls report concerns over their weight and body type (namely, that they're "too fat"), and compare themselves unfavorably to the women they see in magazines and on TV/in movies. The cycle of dieting starts with girls as young as age 9. Also, since the late aughts, the prevalence of eating disorders in teenage girls has increased. Despite what may be some trends in the right direction, girls are receiving a certain set of messages about how they should look, and many of them are taking it to heart.