BioSlim and to a lesser extent Atkins and South Beach make distinctions between "fast digesting" and "slow digesting" carbohydrates.

The fast-digesting carbohydrates, such as bread, pasta, rice, potatoes, baked goods, and candy--raise blood sugar very quickly. This initiates signal to your body to stop burning fat. What is worse, your body also starts storing fat and it starts using this extra sugar for energy instead.

Slow-digesting carbohydrates, such as vegetables and fruits, keep blood-sugar levels normal, which allows your body to continue to burn fat. So, even though pasta (fast-digesting carbohydrate) and a bowl of fruit (slow-digesting carbohydrate) may have the same number of calories, they have very different effects on your ability to lose body fat.