hi Steff,
I think the Carbo Guard is the herbalife product? With fiber and chromium-vanadium? They "might" be helpful, certainly no harm...
Chromium is important for the body's utilisation of insulin, and may help prevent swings in blood sugar. This is the idea behind controlling sugar cravings. The recommended daily dose is 200 mcg (0.2 mg). Vanadium doesn't have a lot of literature to support it's use -- yet.
The fiber may be helpful with blood sugar swings too. My only concern is that fiber generally inhibits the absorption of nutrients taken with it. That's why you should never take your psyllium or metamucil (if you use that) at the same time as your other supplements.
Chromium taken with l-glutamine seems to have a better track record for controlling cravings. You might look into that. I believe the dose for l-glutamine is 1 or 2 grams a day, in divided doses.
Carbs blocker products "may" be effective for blocking the absorption of some starch, but phaseolin is ineffective against sugar. Quackwatcher.com and the FDA have nothing positive to report on these products' claims. Carbs Away suggests eating a low CALORIE, lowish carb menu, around 1,000 cal per day and 100 gm carbs, similar to the Zone, likely the spectacular weight loss claims are a result of the low calorie intake.
Wa'il is right. For Induction and early weeks of OWL, it is best to let the diet itself get your body in the right metabolic state. The addition of some chromium probably would be a good thing. I have found personally that avoiding all sweets, including artificial sweeteners, will eventually curb the sweet cravings. Also, make sure to eat protein with every meal and snack.
Check out this article on Coping with Cravings.
http://www.lowcarber.org/tips/tips007.html
hope this is helpful,
Doreen