Why do vegans crave meat?

Meat is delicious.  I'm not gonna lie, even as a vegan, I admit that I miss eating meat and I miss it quite often.  Why is this though?  The first thought that comes to most people's minds is that I'm not getting enough of the nutrients that I would normally get from eating meat.  Is that really all it is though? 

          Actually, yes, it very well could be.  When the body isn't receiving enough of a certain compound, it will trigger a craving for a certain food that your body recalls having that compound.  However, this usually isn't the reason behind a craving.  Rather, habit and emotions are.  Everyone knows what habit is; a behavior that develops after continued repetition to the point where it is performed practically subconsciously. So, when pertaining to food, eating a certain food every day at a similar time causes your body to become accustomed to receiving that food.  Thus, you crave it every day at the same time because that's just what you're used to.  It makes perfect sense then for a vegan to crave meat if that's what they've eaten for the majority of your life.  Quite simply, your body just misses it.  There's a multitude of other foods that can provide you the same nutrients, but there is never going to be a perfect replica of meat itself.  Even if it tastes good, your body can differentiate between the imposter and the real thing.
            Now then, everyone who's guilty of eating out of boredom or sadness raise their hand.  For me personally, I find myself mindlessly eating all the time.  If it's palatable and there's any room at all in my stomach, down it goes.  Why though?  Shouldn't we just automatically stop when we're full?  Or why is eating one of the first responses that pops up?  In a recent survey, it was found that 86% of Americans crave certain foods when they're happy, 74% crave these foods when they feel they deserve a reward, 52% when they're bored, and only 34% when they're sad or lonely.

            Elevation or maintenance of mood appears to be the main motivator here.  When you're happy, obviously you want to stay happy.  So in turn you would choose a food that makes you feel good, whether that's a cookie or a salad depends on the person.  Same situation when you feel as though you deserve a reward, although tendencies lean toward something that tastes good rather than is good in this scenario (it is a reward after all).

             Boredom is something that I'm sure we'd all love to never have to experience, and when we do try to eradicate as quickly as possible.  More often than not, you want to cure your boredom with something you enjoy.  Eating is something that most people enjoy, and if nothing is else is giving you the illusion of being productive and keeping your hands occupied.  In these situations, the food is usually just whatever is most convenient at the time.

       The post break-up all-I-can-do-is-eat-ice-cream stage is somewhere I'm sure a lot of us have been.  Unlike your ex, food is reliable and stable.  It tastes good, it makes you feel good, and it's something you can control when everything else seems hopeless. 
        To answer why you don't just stop eating when you're full: emotion takes over.  You ignore your stomach and your focus on your emotional well-being overrides any discomfort or biological signals.
        So in the end, yes vegans and vegetarians crave meat.  No it does not mean that they're malnourished. It basically means that their body misses it and the positive connotation that it has psychologically ("Grandma made the best meatballs...").  However, by not eating meat it doesn't mean that they enjoy self torture/denial.  Their reason for adopting a vegan lifestyle matters more to them, and so in turn takes first place above any annoying old habits (most of the time).