When we last looked at Jack in the Box (NYSE:JBX), the company was grilling up some flavorful results for shareholders. Customers apparently kept their hearty appetites as earnings for the burger specialist were up in the second quarter as well.

In the second-quarter report, the company compared its current results with those from the year-ago period, including the effect of stock options expensing. Under this approach, earnings in the year-ago period would have been negatively affected by $0.03 per diluted share, meaning that on a comparable basis, earnings for the present quarter were 17.3% higher year over year. The EPS increase can be attributed to solid comparable same-store sales, improving margins, and a decrease in shares outstanding.

Jack in the Box restaurant comps for the quarter were up 4%, as it benefited from a higher average check as well as increased transactions. Management attributed the gains to its updated menu, which features higher-quality products like entree salads and ciabatta burgers and sandwiches. Meanwhile, comps at its Qdoba Mexican Grill locations were up 5.6% against very tough double-digit comparisons in the same quarter last year.

The company also managed to improve restaurant operating margins by 50 basis points to the current level of 17.6%. Most of these gains came as a result of lower commodity costs, such as pork, beef, and cheese. Jack in the Box also took some credit for the improvement, highlighting its Profit Improvement Program as a contributing factor to profitability gains.

Beyond top-line growth and margins improvements, the third cause of the company's double-digit EPS increase was a reduction in shares outstanding. Although it did not buy back any shares in the most recent quarter, prior repurchases led to an overall reduction in diluted shares outstanding by nearly 5% against year-ago levels. Jack in the Box made no mention of plans to repurchase shares in the remainder of fiscal 2006; nonetheless, because of the positive momentum it has seen management has decided to raise full-year earnings guidance to $2.60 to $2.63 per share, up from the previous level of $2.57 to $2.60.

The growth initiatives from Jack in the Box appear to be right on track. And considering that the company only has a presence in 17 states, there should be plenty of growth opportunities in the years to come.

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Fool contributor Jeremy MacNealy has no financial interest in any company mentioned. Disney is a holding of the Motley Fool Stock Advisor newsletter service.