The U.S. is a hungry nation, and some clever companies are getting rich feeding it. Case in point: GrubHub (NYSE: GRUB), which reported excellent second quarter results on Tuesday.

For the period, the online delivery consolidator posted revenues of $88 million, nearly 50% higher than the $60 million it recorded last year. Net profit, meanwhile, came in at $9.4 million ($0.11 per diluted share), almost 250% better than the year-ago result of $2.7 million ($0.03 per diluted share). On a non-GAAP basis, the bottom line was $15 million ($0.17 per diluted share) versus the year-ago $6.1 million ($0.07 per diluted share). Analysts had not expected this bottom line performance, forecasting just $0.13 per share.

KIey operating metrics also headed north. The number of active diners -- customers who have ordered through the service at least once in the preceding 12 months -- advanced by 42% to hit nearly 6 million, while gross food sales climbed 34% to $568 million.

On the back of such results, the company raised its guidance for fiscal 2015. It now expects to post earnings before interest, taxes, depreciation, and amortization of $104 million to $112 million, up from the previous range of $101 million to $109 million. Its revenue projection was also lifted -- the new estimate is for $358 million to $364 million, up slightly from $346 million to $361 million.

GrubHub offers an online platform for customers to order delivery online from partner restaurants. It currently has over 35,000 restaurants in its system in over 900 cities, plus London. The company had its IPO in April 2014. Since then, its shares have see-sawed in price and are currently down slightly from their first-day close.

The second-quarter results are certainly impressive, and the company is executing well. A problem it will always face, though, is that it operates in a segment with low barriers to entry. Although it has done an admirable job of growing through acquisitions, it is still vulnerable to larger entrants determined to steal some of its market share.

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Eric Volkman has no position in any stocks mentioned.

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