There's a difference between endorsing slimness and liking a picture (that's linked to her twitter) that says 'craving is only a feeling'. It's telling people to ignore their body telling them to eat on the basis of it's just a feeling. That's promoting eating disorders.
If she liked something that was promoting healthy eating and exercise it would be a different response because that's promoting health, she's promoting anorexia.
Indeed, and at least the 'haters' opinions are based on facts, i.e. her public behaviour and her behaviour on social networks. Unless the other poster knows Helen personally I'd be interested to know what he/she bases the assumption that she's a good person with a good heart on.