Is Severe Food Restriction actually a good base for weight loss?

TW: *Body weight, weight loss, eating disorders*

Might sound weird but I feel like so many people online nowadays who are able to live a healthy lifestyle with food and a manageable exercise routine started out by losing weight the ‘bad‘ way (anorexia, bulimia, etc), then slowing increasing food intake as they recovered etc until they achieved a healthier more manageable long term weight.
Obviously this is not the most ideal way but perhaps it is one of the more effective ways?
I guess my question is - is it technically faster to lose weight as fast as possible via the ‘methods’ above and then work up to a better healthier body from there rather than trying to do go down the slow and proper way? (thinking from a purely scientific perspective)