i did strict atkins, 20g carbs a day for 2weeks then I added 5 each week. but if you go above 60 a day you are taken out of ketosis..which is when the body burns fat instead of sugar for energy.
I recently switched to south beach. there are more food options..
and I still am losing! it is low carb in a sense..but also the good carbs.

i found one day of "cheating" I did gain 1 lb but that was gone the next day of being good.