i do not know about south beach, but in atkins:

if you read the old atkins books (the original ones, not the modified ones) atkins gives many many examples of people who eat beaucoup calories and still lost. steadily. one guy ate 5000 calories a day. to me that is on the large side, especially if you are eating veggies (which seem to have hardly any calories) but his point was (and he made it over and over) is to not count calories on atkins, ONLY count carbs.

life does change some when you are finally out of ketosis and into pre-maintenance, etc..........

i am not sure how SBD and atkins compare...... it may not work on SBD