That is true for most people but sometimes not so true for carbohydrate addicts (CAs). Carbohydrate addicts react to carbs. Our bodies don't care whether they are digestible or non digestible they will react any way. The Hellers do mention that in their appearances. That's why broccoli is a no no or something to be watched for a reaction to.

Of course as always CAs are very individual in their reactions. Some CAs can probably get away with using net/usable carbs but many have found that they stall or develop cravings from those foods that become legal using the net/usable carb theory. CAs have the same problem with sugar alcohols which the body doesn't use. We might not use them but we react to them (of course not all CAs do).