My youngest female (almost 2 yrs old), Flea, has this condition. She started overgrooming in the cat shelter (where she was for 6 months), probably out of boredom and frustration. She was found as a 6 month old pregnant feral and taken into shelter. She had her kits, weaned them until they were rehomed and then she (voluntarily) took over another litter whose mom had died. So at 6 -8 months old she had already raised two litters. The vet suggested the hairloss may be hormonal due to her pregnancy and extra long lactation and it may take a while for her body to readjust to normal (She was spayed as soon as the second litter was weaned, about a year ago). Alternatively it could simply be nerves and OCD behaviour. The vet suggested I wait and see and perhaps it would resolve itself once she became settled in. I have tried pheromone collars and feliway diffusers on an ongoing basis, but it seems to have become an ingrained habit. She is now a relatively well-adjusted happy and confident kitty, but still grooms every spare second.

I have now had her with me for alomost a year and there is no improvement. In fact, both her hind legs, front legs, tummy and flanks are almost completely bald. At the time, the vet said I shouldn't worry too much as it is just cosmetic. I don't mind that, because she is still beautiful to me, but I am concerned that the problem may have a more serious underlying cause.
Does anyone have experience with this condition? Does it ever go away?
The hair does not seem to come out at the roots, but seems to be breaking off and only in the regions that she is able to reach with her tongue. The bare skin is not inflamed or crusty or anything like that. Her remaining fur is gleaming and glossy.

Sorry to hear about you cat.

I think you need to identify and eliminate the inciting cause here before you'll see any improvements and based on what's you've said it sounds like excessive grooming is the cause as opposed to hormonal where the hair just falls out and there's no normal regrowth as such. This is also rarer though I can see why it was suspected initially given her history.

Firstly, I would make sure fleas and other parasites are completely ruled out and this includes the environment as well! A positive response to steroids would also more or less point to flea-allergy. You could always start by putting her on a short course. Then I would consider food allergy-again a special diet and based on improvements ( or not! ) would help to pinpoint this.

Yes, one of ours had a flea-allergy and hair did regrow once treated for them!