Is exercise unhealthy?

Introduction
The official UK HAES website cites weight loss and dieting as unhealthy behaviours.

Arguments for
The UK HAES website supports its ideals by linking to a study by Krotkiewski et al, 1978 which demonstrates that adverse effects were experienced by obese women who underwent physical training for 6 months. Whilst some of the participants lost fat over the time period, some of those participants severely obese patients gained weight. It was expressly mentioned, however, that diets was not a controlled factor during the experiments, and as it has been demonstrated to be a key influence on weight loss and gain may speak to the unreliability of the study as a whole.

Discussion
The findings of Krotkiewski et al, 1978