jon357- 20% of ballet dancers having an eating disorder is a massive statistic in itself
Oh that's just a guess, not an official statistic. It's not really measurable, though some studies have said 1 in 5.
jon357- 45kg and 167cm are in the 20%
No. I know a few dancers the same, I don't think they have eating disorders. With an eating disorder they'd likely be around 42.5kg at 167. That isn't nice looking and in a school is not allowed because of requirements and in a company strongly discouraged. Very low weight dancers often can't turn well or hold balances or stay stable etc., none of that is good.
jon357- In the west there are professional dancers who are fatter than average
True, even prima ballerinas (e.g. Núñez, Osipova, Misty Copeland though she's disgustingly bad). The closest to Russia in that way is France and even then not so much. It influences promotions (example, Maria Bulanova is only a second soloist) or a place in a company. This is also the same in other countries, just not to such a level.
jon357- the choreography, the costumes, the staging
Which are often terrible. Look at Paris Opéra Ballet's Don Quixote Act III and compare to Mariinsky or Royal Ballet (RB has beautiful costumes in Don Quixote).