TORONTO -- Loblaw Companies Ltd. (TSX:L) no longer expects to grow its profit this year and says it will be flat compared with 2012, the result of reduced margins as the grocery company focuses on winning over customers in an intensely competitive marketplace.

The company, which owns Loblaws, President's Choice and several other grocery brands as well as the Joe Fresh clothing line, announced its revised outlook Wednesday along with a drop in third-quarter profit.

"In the third quarter of 2013, the company made greater than anticipated investments in targeted food categories as a result of an increasingly competitive environment driven by greater than historical square footage expansion," Loblaw said in a statement to investors.

"The company remains committed to its strategy to drive its customer proposition, including investments in food margins, in the fourth quarter of 2013."

Translated, that could mean good prices for shoppers as Loblaw competes against other domestic grocery chains, primarily Sobeys and Metro, and U.S. retailers such as Walmart, Target and Costco.

Shares in Loblaw fell more than six per cent or $2.97 to $44.87 at the open on the Toronto Stock Exchange.

Loblaw executive chairman Galen G. Weston, whose family is the biggest shareholder of the Toronto-area company, said same-store sales have increased three quarters in a row.

"Unfortunately, due to incremental margin investment in the back half of the year, we are lowering our earnings growth expectations for 2013," Weston said.

The company is also introducing three new financial measures beginning with the third-quarter report, that weren't used in previous guidance -- making comparisons with previous estimates more difficult.

In the third quarter ended Oct. 5, Loblaws had $154 million or 55 cents per share of net income, a standard accounting measure, down 28.6 per cent from 77 cents per share a year earlier.

Its adjusted earnings, one of the new measures that excludes items that are part of standard accounting, was $220 million or 78 cents per share, down 3.7 per cent from 81 cents per share.

Revenue for the 16-week period was up 1.9 per cent to $10 billion. The earnings came in below what analysts were forecasting, according to Thomson Reuters.

During the summer, Loblaw spun off its real estate holdings into a new publicly traded trust, Choice Properties (TSX:CHP.UN), which remains majority-owned by the grocery company. Choice's publicly-traded shares were up a penny to $10.21, higher than the $10.05 price it had on the first day of trading on July 5.

Loblaw is also in the process of acquiring Shoppers Drug Mart (TSX:SC), which will be operated as a separate division with complementary products. Shares in Shoppers were down $1.70 or 2.78 per cent $59.35, up from $48.40, prior to the announcement of the friendly takeover on July 15.

Irene Nattel, an analyst with RBC Capital Markets, said that Loblaw's results were an indicator of how intense the competition has become in the grocery sector.

"Further investment in margin is required to sustain top line (sales) performance," she wrote in a note, adding that the Shoppers acquisition will help the grocery giant "broaden" its revenue and earnings next year.

Separately, Metro Inc. (TSX:MRU) reported later Wednesday that its sales for its fiscal fourth quarter ended Sept. 28 were down 1.1 per cent from a year earlier, same-store sales were down 1.8 per cent, but adjusted net earnings from continuing operations were up.

Montreal-based Metro also announced its dividend will rise to 25 cents per share, an increase of 16.3 per cent. Metro shares dropped $3.21 or 4.9 per cent to $62.50.