[CuriouslyC]

Some do, some don't.

One of the big wins for low carb high fat diets is that people tend to self regulate better. I hear people say "I ate as much as I wanted and I lost weight" all the time. Thus it is important that calories also be controlled.

The big issue with carbs is that when you have too much glucose floating around, the liver responds by converting it into palmitic acid. Palmitic acid seems to be one of the worst saturated fatty acids in terms of metabolic effects, and hepatic fat production tends to result in increased levels of low density lipoprotein. Fructose is even worse than glucose in this respect, as its primary metabolic fates are hepatic glycogen storage (which is very limited) or conversion to fat. Note that these issues only occur when you consume carbohydrates in excess of your body's ability to readily store or metabolize them - consumed in moderation, carbs are just fine.