I would definitely recommend the high protein, low in sugar. There are a lot of bars out there that are very high in sugar 20 plus grams.
A great bar is the MHP Macrobolic very low in sugar, great tasting and definitely filling, check it out another good one although not as good tasting is the Universal Nutrition Dr. Carb Rite Bar if you are worried about the carb content .
Whatever you decide to take, remember they are meal replacements, so don't abuse them. Also remember they are no replacement for sound nutrition found in every day foods like tuna, eggs, chicken etc...
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