I think perhaps you meant 'low carb bars' - low carb shakes are generally protein shakes, and they do not have the same effect as 'low carb' bars as they do not possess the sugar alcohols/glycerine that the bars do.

Low carb protein shakes are a good way to supplement a low carb WOE and they make a good alternative to breakfast if you're not up to eating first thing in the morning.

Nat