What does Phase 2 do? Phase 2 acts to prevent the carbohydrate digestive sequence from occurring in the body as usual because it has a neutralising effect on the alpha amylase enzyme. This means it prevents it from carrying out its normal function of breaking down starch and converting it into sugar calories. By blocking the action of alpha amylase, the presence of the Phase 2 carb-blocker allows carb foods to be processed by the digestive system with an effectively sharp reduction in the actual calorie intake.