While the net impact of lower fuel prices is a hot topic for debate, one industry is already seeing a boost: restaurants.

As people spend less money on gasoline, they're spending more money on other discretionary items, including going out to eat and drinking at bars, according to recent economic data. Such spending rose 0.8 percent in December over November, according to the Commerce Department. The increase came despite a 0.9 percent overall decline for retail sales during that period.