I think that is one of the reasons Atkins states to make sure you follow the carb ladder, or at least just add one new food in at a time. That way you have time to see how your body reacts.

It also takes some experimentation and just learning to read your body. I found out cream stalled me by reading the signals my body gave me more then the scale. When I had cream I would instantly crave more. Even if I was full having some cream as a dessert would make me want to eat more. Weight loss wasn't as good of an indicator because it was anything but steady normally. I had ups, downs and flat lines on the graph.

Eliminating the majority of foods form your diet then slowly adding them back in is a great way to see what foods you are sensative too and what can stall you.