Sorry, but this just isn't right. 20g carbs of sugar plus a 5g fiber pill is absolutely not the same as 25g carbs of spinach containing 5g of fiber, even though the net carbs are the same. The reason that fiber moderates insulin release in the spinach is that its carbs (e.g. natural sugars and starches) are actually locked up inside the plant cells, whose walls are made of cellulose fiber. Your digestive system literally has to break open the cells to get at the carbs, which takes some time and thus moderates the insulin release and blood-sugar rise. A fiber pill doesn't make the sugar physically inaccessible in the same way, so it goes straight to your bloodstream anyway, and your body just gets around to digesting the fiber pill later. 20g of sugar *will* negatively impact your weight loss no matter how much fiber you consume it with, because the fiber isn't structurally integrated with the sugar and thus won't moderate its glycemic effects. You'll still absorb all 20g very quickly, while the absorption of the 20g of spinach will be spread out over time while your body breaks down the plant cells.

Remember, the whole point of Atkins is to control your insulin balance, and so we pay attention to glycemic index as well as total carb count. Keeping the total carb count down is a good first step, but you also need to focus on getting those carbs from low-GI foods. There is no way to make 20g of refined sugar low-GI, or to block or reduce its net carbs, not with fiber supplements, "sugar blockers", or anything else. There are even differences among GI ratings for various types of refined sugars -- the reason high-fructose corn syrup is so evil is because its glycemic index is higher even than table sugar! So no, a carb is not just a carb, for weight loss or nutrition.

There is a FAQ about this on the Atkins web site at http://atkins.com/helpatkins/faqs/faqfood/index.html.