Consuming calories in liquid form may be the most efficient way to keep your calorie count up, but sports hydration does not offer that sated, satisfying feeling that solid food provides. For shorter duration events, you might be able to get away with fewer calories, such as a carbohydrate and electrolyte solution. For longer duration activities, experiment with bringing your favorite snacks on the bike to keep your energy stores topped off.
Pro Tip: The most important consideration when selecting an on-the-bike hydration option is accessibility. Anything, like bottle placement, that might detracts aerodynamics is less than the penalty you'll suffer if you become dehydrated from not reaching for a bottle.