Eating two large medjool dates as a pre-workout fuel as opposed to starchy carbs is an excellent way to efficiently power through a workout. Dates are almost pure glucose, which the body absorbs quickly, and give you a quick burst of easily used fuel instead of getting stuck with excess carbs, which take more time to break down and can lead to weight gain. Getting most of your carbs from glucose-rich fruit such as dates is a wise strategic pre-workout approach when trying to shed abdominal fat.
Note that it's worth thinking of dates and other high glucose/GI foods the same way that drag racers look at nitrous. They're great for a quick burst of energy, but they should only be eaten if you have regular slower burning fuel handy throughout the day or you'll conk out (or crash). Overall, grazing on glucose-rich foods during endurance sports is a good fueling strategy, because glucose burns extremely efficiently and requires little digestive energy.