Hi,
Ice cream is both high glycemic and high fat, so naturally your concern is understandable as fat + insulin in your blood at the same time will cause some to be shuttled into fat cells. So how can ice-cream still be allowed? It’s all down the timing. If you eat the ice-cream towards the very end of your CN/CBL (e.g. as a desert) you will not run into this issue. How/Why? Because the insulin spike caused by the high glycemic carbs (i.e. sugar) in the ice-cream will only last 1-2 hours immediately after consumption where-as the fat in that ice-cream will hit your blood stream until some hours later, thus avoiding the insulin spike which would otherwise cause a fat storage promoting environment (i.e. simultaneous fat + insulin in the blood).
This is why Kiefer advises consuming low fat in the first meal on CN/CBL and reserve the high fat carbs (e.g. ice-cream, etc) towards the end of the evening, thereby circumventing the possible issues of high fat + high carb.
Hope that answers you question. 🙂