On Thursday, two of the world's largest food retailers will report their 2012 financial results and, more importantly, try to convince investors their moves to improve their operations in key markets can pay off.

In Paris on Thursday morning, combative Carrefour CEO Georges Plassat will outline the French retail giant's 2012 numbers. We already know Carrefour's sales for the year; growth in Latin America helped offset lower underlying sales in Europe, France and Asia.

However, Carrefour's group like-for-like sales in 2012 were flat. 2012 was a year when Carrefour saw sales in its core hypermarket business in France fall, when it was hit by the economic problems in Spain and Italy and when even sales in China were down.

The retailer expects to file underlying operating income of EUR2.07bn for 2012, down from EUR2.7bn a year earlier, and analysts, investors and the media will head to the French capital to hear if Plassat's early initiatives (he took over in May) are bearing fruit.

Carrefour has claimed sales improved in France in the back half of 2012; in the fourth quarter, food sales in its hypermarkets rose for the first time in two years. However, more colour is needed on how much Carrefour will need to invest in France to further boost sales and compete head on with rivals like Leclerc, which increased its share of the country's grocery market in 2012. And that is before Carrefour tries to revitalise sales in southern Europe and over in China. The Chinese economy slowed in 2012; can Carrefour's falling sales there be pinned on that?

Plassat has already shaken up Carrefour, with moves to quit markets to free up cash to invest in its core businesses. But the task of revitalising a retailer that has under-performed for years is a very difficult one.

Later on Thursday afternoon, further north Brussels, Pierre-Olivier Beckers, the chief executive of Belgium-based retailer Delhaize, will present that retailer's numbers for 2012.

Like Carrefour, Delhaize published its sales figures in January and all eyes were on the US, where it generates almost two-thirds of its revenue. The company's comparable-store sales fell in the US in 2012 but the retailer saw some improvement in the fourth quarter thanks to its work to "reposition" the brand perception of its Food Lion banner and better "volume trends" at a second US chain, Hannaford.

We have to wait until Thursday for profit numbers but in the period to the end of September, Delhaize booked a 19% slide in operating profit for its US business.

Delhaize's US operations are going through something of a shake-up. A new local management team has been in place since December, which is busy trying to improve the performance of the business.

As well as the work to improve the Food Lion brand and to cut prices at Hannaford, Delhaize is expanding its Bottom Dollar Food discount chain and is reducing the workforce across its operations. Last month, the retailer said 500 jobs in the US would go. Plenty then for Delhaize to discuss and the market to analyse.

And, of course, a retailer with over 1,500 stores in the US will have plenty of insight on trading conditions there. The noises out of the US have been mixed in recent weeks, with Wal-Mart cautious about its short-term prospects there but supermarket rival Safeway more optimistic.