Why anyone would want to emulate Kate Moss, who apparently survives on a diet of cigarettes and photons emitted by photograper's flashbulbs, is a mystery, but apparently they do. Because she's thin and rich and has a glamorous life, I guess. The Telegraph says:

Ordered by the ASA? Don't think that has any legal weight. Zazzle says the saying did not appear on children's clothes, so the first line of the piece is a bit misleading.