Severely Underweight.

If they blame it on you being veg, just say you're still not going to eat meat so they'd better think of another way to help you because there are ways to help, some docs can be pretty stubborn/ignorant about that and believe that you need meat to survive.

According to my BMI chart, 15 is pretty darn underweight- regardless of weight or height.

Are you trying to gain weight?

I has solution. Om more Noms. Nuts esp. Kilos of them.

Can't gain a Kilo of anything from a Kilo of salad.

1. You couldn't eat a Kilo of Salad in a sitting.

2. Most is ruff-age or water.

So imagine how much you'd have to eat to gain a Kilo of flesh... hence protein rich foods are easiest to gain more residual weight from.

Legumes and Nuts... Eat a Kilo of Baked Beans a day and see if that works
You might gain a Kilo in a week, although you're using the mass as energy during this week also.

I suggest lots of wholesome winter soups with lentils.  Stacks of veges.

Put Olive Oil on everything I suppose. Eat bunch of Bananas a day and some Avocados.
You could probably just accomplish a decent BMI from Gorilla diet... of fruits and berries.

Banana Smoothies with Protein rich things like Cashews or Enriched Soy milk (ew, soya).

Anyways, is the Doctor the relevant person? Do you feel it is an unexplained absence of weight, like you say.. you've always had this type of metabolism?

Obviously you don't Nom enough Oms for your body to retain any for storage.

Why not see a dietitian? Unless you want a 'yep you're underweight, give me 80 bucks please'.. 'oh while you're here I can hook you on some drugs too? new, just out of the lab, needs to be tested ya kno'.

 I mean... you could get a blood test to cross off any parasites causing the 'extra' weightloss and lacking gain from what you eat. And Iron, B12 and all the other general key markers too.

But maybe just go to a dietitian for food ideas, I suggest. If not type some shit into google ^____^

How much food do you eat and how much exercise do you do?
To you it may seem like a lot of food when it's not. Or I might be completely wrong.
If you do minimal exercise perhaps up your carb and protein intake and try to gain some muscle??
Sorry I can't help you much. I'm a healthy weight according to the BMI, but I have always had a little around my waist, so gaining weight is not a probelm to me.
Have you ever seen someone about your underweightness??
I don't know much about metabolisms, but perhaps yours is stuffed up because of a disease?
Although saying that. My best friend is super skinny, and so was her dad when he was her age. But now his overweight. It could be just your genetics.
My advice is to try and find out why you can't gain weight. Because this will probably help you a lot in gaining weight.

Sorry. I don't think I've helped you much.
P.s if you say you were the same before becoming a vegetarian but your weight just being stressing you out lately (and if you are that you be bullied) the doctor shouldn't link it to you bring a vegterian. If they do though, get a new doctor.

You could consider seeing a nutritionist/dietician. There are a few around who specialise in vegetarian nutrition. They would get where you're coming and probably be able to give you some advice that doesn't clash with your ethics. There are a few contacts listed on Veg Network of Vic's website: http://www.vegetarianvictoria.org.au/healthy-living/dieticians.html

According to my BMI I'm malnourished! Which is ridiculous. These things need to be taken with a grain of salt. If you've never worried about it before and are only now worried after finding out your BMI. I still wouldn't worry.. it's obviously not making you sick or causing damage if you haven't realised before! That being said, always go to the doc if you're worried. I'm sure they won't put it down to being veg. Btw were you the same way before you went veg? Because I was. I've always been tiny. Sometimes doctors won't believe me when I tell them my weight and others don't but they've never been worried about it or thought much on it. Everyone's different. Just so long as your healthy and eating enough you shouldn't be worrying about your weight. But still, go to the doc.
Keep us posted and good luck!

I would find a nice vegan protein shake and start consuming them between meals.

Oh yeah! I learned that doctors only get 3 HOURS of nutritional education in their whole career!