* Plans to split consumer electronics and food businesses
* Food business sales revenue boosted by stronger Russian rouble
* FY outlook restated for consumer electronics unit
* No new outlook for food business to be spun off
* Metro shares down 3.6 pct (Adds detail, shares, analyst and CEO comment)
By Emma Thomasson
BERLIN, May 31 (Reuters) - German retailer Metro reported a loss at its consumer electronics division on Wednesday, citing heavy investment before the business is split from the company's food operations, sending the stock down more than 3 percent.
The group changed the way it presents its figures because of the planned break-up, which it has said is aimed at creating independent companies able to pursue more acquisitions and boost the valuation of the businesses.
Metro expressed optimism that a Duesseldorf court will rule against shareholder challenges to the company's plan to spin off its cash and carry wholesale and Real hypermarkets operations from the Media-Saturn consumer electronics arm.
Chief Executive Olaf Koch said he expects the demerger to be completed "weeks" after the court ruling due on June 22.
The consumer electronics business -- to be renamed Ceconomy -- made a 19 million euro ($21.23 million) loss before interest, tax and special items (EBIT) in the three months to March 31. That compared with a forecast for a profit of 24 million euros in a Reuters poll of analysts.
Metro shares fell 3.7 percent to 29.48 euros by 0748 GMT, among the biggest fallers on the German mid-cap index.
Analysts at Jefferies, who rate the stock a "hold", said the group was suffering on several fronts, including its exposure to the weak Russian economy, a tough environment for hypermarkets and a competitive German consumer electronics market.
"The emergence of two more-focused, separate businesses should be welcome at a time when operational performance continues to be patchy," they wrote in a note.
Metro said the loss was because of investment in areas such as IT as well as start-ups. Sales at Ceconomy fell 0.5 percent to 5.26 billion euros but were up 0.3 percent on a same-store basis, boosted by strong growth in Germany.
Online sales jumped by more than 40 percent to account for almost 12 percent of total sales.
With the results to be the last before the proposed split, Metro adjusted its forecast for the financial year to Sept. 30 to relate exclusively to the consumer electronics business, saying it expects a slight increase in overall sales and EBIT.
At the cash and carry and Real unit to be spun off, quarterly sales rose 2.4 percent to 8.5 billion, helped by a stronger rouble and acquisitions including the Pro a Pro group in France.
EBIT before special items after depreciation or amortisation rose to 132 million euros, including an 80 million euro boost from a real estate deal in China and 24 million euros from positive currency effects, largely down to the stronger rouble.
It gave no new outlook for the food business. ($1 = 0.8951 euros)
Additional reporting by Matthias Inverardi; Editing by David Goodman