I started my 3 week pre-op diet this past Monday (Jan. 20th). I am allowed up to 250 cal of low glycemic veggies and can add some spices/vinegar if desired. I'm also supposed to have 3 protein shakes, and can have some caffeine free black coffee/tea with artificial sweetener. So far, I have lost 12 pounds in 5 days. Is this normal? I haven't been any more active than usual.

yes. My pre-op diet was two weeks long and I lost 20 lbs, and I do remember losing a little more the first week than I did the second week - so 12 lbs for week 1 sounds about right.

Yes, I had one week liquid diet with 1 cup of fruit or vegetables twice a day and I lost 12 pounds.

Yes, it's normal (although everyone is different). I also find that the heavier a person is, the more they lose on these types of diets. I've noticed this not only on sites like this, but also when I was a part of weight watchers. People who were morbidly obese had very large drops of weight on any kind of restricted diet (10 pound or more a week), where as that would be both unusual and alarming for anyone who was within a normal BMI range. The first time I did this I lost 21 pounds in 21 days during my pre-op diet (of course it was not one pound a day, it stalled and dropped over 3-5 days usually, but the end result was this). I'll be starting my pre-op for my revision surgery in February, so hopefully I can get similar numbers.

Very normal you'll drop a ton of water fluid weight in the first month...

I lost 20lbs in the first 2 weeks diet