Bob, because he is buying the underlying, is said to have entered a long forward contract. Allaz and Vila suggest that there is also a strategic reason in an imperfect competitive environment for the existence of forward trading, that is, forward trading can be used even in a world without uncertainty.
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There are a few that appear to be mildly effective. This includes Caffeine, Green Tea and Glucomannan (a fiber that can reduce appetite). However, the results are usually weak and inconsistent and certainly nothing to get excited about.