Buddhist monks and nuns in the Theravadan tradition do not eat after noon but I suspect they're not running around as much as we do or spending much time on the treadmill. If it works for you and you're healhy, I don't see a problem. I'm just the opposite--I need to eat several small meals or my blood sugar drops and I feel lightheaded and can't function. Everybody's different.
Every body has different requirements that need to be met in order to function properly. There are many many people that will tell you that you need to eat 2000 calories a day, but this is only an estimate, and may not be appropriate for your age, health status, and activity level. You may find that you feel fine on far less than that, and that eating once a day works for you. As long as you do not have blood sugar issues, do not feel fatigued throughout the day, and are getting adequate nutrition, do what works for you. There are no cookie cutter diets or lifestyles that you need to conform to.
Well since this thread I been eating twice daily w/ a snack of a banana either to start the day or in between the meals. I think it's too much b/c well...
...i sorta... it tried to come back up. I'm not very active. 1 30 minute walk a day is all that I do.
I'm convinced about what previous repliers to this said about not absorbing RDA of nutrients. That thought just scares me. I do appreciate the contradictory posts though b/c I did feel okay eating once daily. It was only dinner that I was eating. I'd perform all my daily activities on 1 cup of coffee and water until around 6 o'clock PM when I'd eat. At first doing this caused headaches and like you said, lightheadedness, but after a few weeks it was fine.
Then somebody took my picture a couple weeks ago. I have like no fat on my hips or legs, yet my belly is protruding from bloat. It made me think eating once a day was causing that (some type of starvation mode?). Then again my shirt was a babydoll style and they do that.
Now I'm undecided again. Oh well. I feel okay both ways, either eating once or multiple times. I think the combination of sugar and spicy caused the nausea I mentioned. We're talking about habanero sauce and then going to pina colada cake. (made it myself. )
I think the fact that your banana tried to come back up again is a sign you are definitely not eating enough - this really should not happen. I'm really, genuinely concerned for you Ragdolly, as surviving on one cup of coffee until six o'clock is not sufficient fuel even for a moderately active lifestyle. You may feel fine now but I fear you are heading for trouble if you continue in this way.
Of course, there is no 'one size fits all' when it comes to diet but there are some basic nutritional facts that we cannot get away from. Based on what you have said, you will certainly not be getting what you need nutritionally from your diet and you are putting your organs under a huge strain by doing this.
Seriously think about seeking some professional advice from a registered vegan (or at least someone well versed in the vegan lifestyle) dietician/nutritionist. We can all sit here and speculate about whether your diet is damaging your health but until you get yourself properly checked there's no real way of knowing.
I would recommend a smoothie in the morning if you can't handle anything solid. You don't have to drink it as soon as you've woken - wait until you are somewhat ready and don't force it down. You may have to work at it for a while before you can drink a whole one in one sitting - it sounds to me like you need to retrain your body to handle food at certain times. It may also be psychological.
Maybe try having a small salad sprinkled with seeds, a little avocado and some beans for lunch. Again, initially you might only be able to eat a very small amount but everyday will get easier.
Like Powerlifer said, your body cannot absorb everything it needs in one sitting. I urge you to consider upping you food intake and adopting a balanced diet of three meals a day - worried about you:(
Multi-vitamins are usually synthetic and yeah there not brilliant but that doesnt mean there useless. They just shouldnt be viewed as an alternative to a healthy diet, they are merely to supplement a good diet.
Glad your getting on better. B12 is a good one if your 100% vegan as there is no dietary source. Zinc is another hard to get mineral on a vegan diet, if using large doses for long periods be sure to supplement copper.
Calorie restriction is well known to extend life in laboratory mice (who generally lead sedentary lives like we do). There is even a society for people who believe in increased longevity through calorie restriction (crsociety.org). Low calorie, low protein diets have also been shown to reduce cancer risk. However it is important to make sure that you are eating a nutritionally optimal diet - being vegan is a good start here, taking a high quality multivitamin would be a good precaution.
Based on your height and weight it looks like your calorie requirements would be around 1400 - you can plug your age in to my calorie expenditure calculator to get a more accurate number.