Why do they look hungry all the time?

Vegans (like some homosexuals I've met) seem to think that everyone cares about what goes in their mouths.

'But veganism is the healthiest way to eat!'

Oh, you're finished? well allow me to retort.

Ethical arguments aside, this logic is based on what science?
'Eat food. Not too much. Mostly plants.' Read all the words. Mr Micheal Pollan is credited with this quote and he knows more about food than most people. Getting the right amount of nutrients from Vegan only foods means eating all day. Like a gorilla. Which is an argument that is brought out from time to time by the anti-carnivores because Gorillas are vegans. But to continue that argument - 'Gorillas are humans closest living relatives after chimpanzees'(1) and 'Human beings separated from chimpanzees 6 million years ago, and from gorillas about 10 million years ago' (2). 

Not to scale.

So using the gorilla as the closest related primate because unfortunately for vegans
'While the common chimpanzee is mostly herbivorous, it does eat honey, soil, insects, birds and their eggs, and small to medium-sized mammals, including other primates.'(3) That terrible 'mostly' word again.
Comparing the two, 'Gorillas spend about 14 hours feeding and foraging and about 10 hours resting every day. Gorillas move about 400-1,000 meters (0.24-0.60 mi) per day.'(4) while
'Chimpanzees may spend half of their day feeding, and shift from one food type to another even before the first type has been depleted' (5).
 

Sure. Let me just eat 20 kilos of veges today so we're on the same page.

Based on the gorillas lack of movement and the fact they have to eat all day to support it, should be concerning enough. If vegans (or any human) were to implement this style of eating, ie 6 small meals + a day - they'll see insulin spikes after each meal with no stability and 'group of normal-weight test subjects who ate 6 meals a day exhibited significantly higher blood sugar values than those who ate 3. Despite eating the same amount of calories, the fewer meals group had 30% lower blood sugar values than those who ate 6 meals'(6).

Are vegans able (allowed) to eat grubs, termites and ants (Gorillas do) or does that fall under that vegan mantra: 'I will not eat anything that walks, swims, flies, runs, skips, hops or crawls'

To maintain a balanced vegan diet, it's necessary to add 'fortified' food/drink and vitamin pills, which has to be concerning when it's not possible to derive all required nutrients from natural whole foods - kind of ruins an argument for 'Health' if it's supplemented. Coma patients have a supplemented diets. In strict vegan lifestyle Vitamin b12, protein, calcium, vitamin D, iron, omega-3 fatty acids and iodine that if not monitored can lead to many health related issues (appendix A)
 
Maybe, a vegan diet (done right) could be used as a short term detox - if you're into that hyper-correction of poor life/diet choices thing. 

Food for thought. "Although the brain accounts for less than 2% of a person's weight, it consumes 20% of the body's energy."(7)  An average person needs between 2,000 and 2,500 calories a day to maintain their weight. Around 400 calories a day to the brain (see appendix b for 400 calorie snacks(meals?)). From an evolutionary stand point, scientists draw a direct link between meat eating and expansion of homo sapiens' brain size- " was this new meat diet, full of densely-packed nutrients, that provided the catalyst for human evolution, particularly the growth of the brain, said Katharine Milton, an authority on primate diet (8).

A comparative analysis on both vegetarians and omnivores was completed by Dr. Weston A. Price.
'Dr. Price traveled the world in the 1920′s and 1930′s visiting 14 isolated cultures in the process.  During this adventure which he documented in great detail with amazing pictures in his masterpiece Nutrition and Physical Degeneration, Dr. Price concluded that while the diets of these natives varied widely, nutrient dense animal foods high in the fat soluble vitamins A, D, and K (also known as Activator X) were the common denominator.  Consumption of these animal foods were revered in these communities as they bestowed vibrant health, ease of fertility, healthy children, and high resistance to chronic and infectious disease.
This discovery was a disappointment to Dr. Price who had expected to find the vegetarian cultures to be the healthiest cultures of all. But, the vegetarian cultures he examined displayed more degeneration than the omnivore cultures which surprised him given that these vegetarian cultures did indeed have superior health than the Americans of his day'(13)
  
Relating to the title of this post, without plenty of healthy fats in your diet, you are not able to assimilate and absorb the nutrients in fruits and vegetables, so their not soaking up the goodness that the diet offers. Might explain why %75 of all vegetarians return to meat eating (15). After all, 60% of your brain and nervous system are made of fat. We need fat for proper brain function, nerve signal transmission, and hormone balance. Interestingly (not relevant), doughnuts, french fries, corn chips, and lollipops can qualify as vegan.

Veganism for health - see above.

PS. Absolute respect for ethical veganism and I like gorillas.

Appendix A:

 
- Vitamin b12 deficiency: Hypocobalaminemia. 
- Protein deficiency can lead to variety of ailments including mental retardation and kwashiorkor (9)
- Dietary calcium deficiency, which can lead to depleted calcium stores in the bones, thinning and weakening of the bones, and osteoporosis 
- vitamin D deficiency has been associated with rickets, a disease in which the bone tissue doesn't properly mineralize, leading to soft bones and skeletal deformities. (can be mitigated to a degree with regular exposure to sunlight) 
- Iron deficiency can lead to anaemia if not noticed in the earlier stages(10) 
- Symptoms of omega-3 fatty acid deficiency include fatigue, poor memory, dry skin, heart problems, mood swings or depression, and poor circulation (11) 
- iodine deficiency gives rise to goiter (so-called endemic goiter), as well as cretinism, which results in developmental delays and other health problems

Appendix B

- 227g steak = 400 calories
- Rice and beans; One cup of cooked medium-grain brown rice and half a cup of black beans offers 110 calories. and some veges = 400 calories 

- Quinoa and Veggies. One cup of cooked quinoa. Mix it with some roasted veggies and tofu = 400 calories.

References:

1. Nature, sally et al. (2012) "Insights into hominid evolution from the gorilla genome sequence", retrieved (14/12/212), http://www.nature.com/nature/journal/v483/n7388/full/nature10842.htm.
2. Goodall, Jane (1986). "The Chimpanzees of Gombe: Patterns of Behavior". ISBN 0-674-11649-6. 3.Doran-Sheehy D, Mongo P, Lodwick J, Conklin-Brittain NL. Male and female western gorilla diet: preferred foods, use of fallback resources, and implications for ape versus old world monkey foraging strategies. Am J Phys Anthropol. 2009 Dec;140(4):727-38.
4. Seaworld, (2012) "Gorillas - Behaviour", retrieved (13/14/2012), http://www.seaworld.org/animal-info/info-books/gorilla/behavior.htm
5. lpzoosites, (2005) "Chimpanzees" ( 13/12/2012), http://www.lpzoosites.org/chimp-ssp/chimpanzees.htm
6. Holmstrup, et al, 2010
7. Drubach, Daniel. "The Brain Explained." New Jersey: Prentice-Hall, 2000.
8. Berkley, Katharine Milton,  (1999) "Meat-eating was essential for human evolution", retrieved 11/12/2012, http://www.berkeley.edu/news/media/releases/99legacy/6-14-1999a.html  
9. Michael C. Latham (1997). "Human nutrition in the developing world". Food and Agriculture Organization of the United Nations.
10.Better Health, (2012), "Iron Deficiency", retrieved 11/12/2012, http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Iron_deficiency_adults
11. University of Maryland Medical Center (2011), "Omega-3 Fatty acid", retrieved 14/12/2012, http://www.umm.edu/altmed/articles/omega-3-000316.htm
12. The Lancet (12 July 2008). "Iodine deficiency—way to go yet". The Lancet 372 (9633): 88. doi:10.1016/S0140-6736(08)61009-0. PMID 18620930. Retrieved 2008-12-05.
13. Laurel of Leaves (14/12/0212), "A vegan diet is not healthy", retrieved 14/12/2012,  http://www.laurelofleaves.com/2012/04/a-vegan-diet-is-not-healthy/
14. Psychology Today, Hal Herzog phd, (2011) "Why Do Most Vegetarians Go Back To Eating Meat?" retrieved 15/12/2012, http://www.psychologytoday.com/blog/animals-and-us/201106/why-do-most-vegetarians-go-back-eating-meat