I saw a really interesting tidbit in the new issue of EatingWell (which, BTW, is a great magazine: good recipes, and great nutrition info) that really hilights the fact that what you eat is at least as important as how many calories you eat. 

Anyway, a study took a group of overweight men and women and put them on 1,000 calorie-a-day diets.  Half of those calories were from the same foods for all the participants.  The other half came from different sources.  Half the people got those calories from complex carbs like pasta and bread, the other half got the same number of calories from almonds.  The almond people lost 62% more weight, and more body fat. 

That's pretty dramatic.  That's why the whole low-glycemic thing makes sense to me.  I think the biggest problem with low-carb versus low-glycemic is that low-carb encourages people (since most people don't think very carefully about it) to eat lots of calories in the form of fat, which has other consequences.  Just because you aren't eating carbs doesn't mean you aren't eating calories, and no matter what food you eat, if you eat more calories than you burn, you won't lose weight.  The key to the low-glycemic diets is that you encourage your body to burn the fats you are eating, so that you are burning all the calories you are eating instead of storing them in favor of burning carbs.  That's true of low-carb diets too, but my personal feeling is that low-glycemic diets encourage healthier long-term eating habits as opposed to the either all meat or all fake foods that people tend to fall into on the low-carb diets. 

That said, I eat my fare share of low-carb protein bars, sweets, etc.  But I also try to get good low-glycemic whole foods that are nutritious.  It's tough on a busy schedule, but it can be done.