As others have stated already, its pretty clear that the core reason for this veg diet isn't for treatment of any psychiatric d/o, but to encourage malingerers out. I'm just an amateur nutritionist, but I think vegetarian/vegan diets are not healthy. Yes, ALA, a form of Omega-3 PUFA can convert to EPA/DHA, but does so in a very inefficient manner. You're better off getting your EPA/DHA from marine/animal sources and/or supplements. Furthermore, theres more evidence supporting the benefits of not just Omega-3 PUFA, but saturated fats in maintaining cardiovascular, neurological, and mental health.
As for malingering, I think there are better methods. But yea, it sucks that EDs have been the place to go when people get kicked out of housing. Usually its because they simply don't want to follow certain rules such as...not being high or drunk.
How sad it is that there are people who are willing to get stuck, change into paper scrubs, and be forced to lie to a bunch of people so they can get shelter and food. What an existence.
The problem isn't lack of shelter or food for many as you stated. If there was absolutely no shelter or food, I'd be much more open to taking people in. The problem is the patient often times prefers not to be in the shelter because they find the hospital more aesthetically pleasing. Sometimes the patient was in a shelter but was kicked out because they sexually assaulted (or did some other anti-social behavior) and now sees the hospital as their next recourse. Oh great, now I've got to allow this sexually dangerous guy on to a unit when I don't even believe with strong certainty that he's severely mentally ill? No way.
(By the way, if you think such as guy should be on the unit, please tell me why cause I see a lot of doctors still admit this type of patient while even agreeing with me that he is not mentally ill in a sense that warrants hospitalization. Please give me your reasoning.)
Homeless shelters, while we're at it, are usually better places for such people because 1-in accordance with Linehan's work the person should suffer the consequences of their actions as part of the learning experience and 2-Many homeless shelters have programs that will lead to the true path of elevating the person. That is incentives and programs to get such as person an education, jobs, and structure.
For someone with immature defense mechanisms, the diet could ultimately be of some use. Malingerers often times have emotional issues, but yes, that's not the primary purpose I'm proposing it. If it provides the patient with a benefit, so be it and that's a good thing.
What you said is true regarding the theory behind omega FAs. EPA is the main known omega FA that provides benefit. There are vegetarian sources of it such as sea algae oil though they are not as readily available in the market or as cheap as fish oil. One could simply remedy that by providing a vegetarian diet plus a fish oil supplement.
Furthermore, theres more evidence supporting the benefits of not just Omega-3 PUFA, but saturated fats in maintaining cardiovascular, neurological, and mental health.
There's always some data that can emerge that can go against the medical establishment. Sometimes this data even turns out later to be the real truth vs what was previously held as convention. E.g. Accupuncture was widely rejected by western medicine despite the plethora of scientific data that it worked that later emerged.
Yes there's some argument here or there with some actual data that a saturated fat diet could have some benefits though this has not broken the convention as far as I know. When I say convention, I mean evidenced-based held beliefs. There's plenty of data that, for example, high LDLs are bad for you, but then you occasionally see a study showing that saturated fats are not bad or even possibly beneficial. The debate goes on.