Town centre supermarkets had lost about £12million in trade to other stores, a planning inquiry for a new Sainsbury's store has heard.
Braintree Council is concerned that if the large supermarket is built on the Broomhills Industrial Estate in Braintree, it will take even more shoppers away from the heart of town.
Sean McGrath, a director of Indigo Planning, which works with Sainsbury's, said Braintree town centre had lost about £42million in trade in recent years.
He said supermarkets within the centre, such as Sainsbury's and Tesco, had lost about £12milliion collectively to Lidl, Tesco in Great Notley and Marks Farm, and Sainsbury's in Stanway and Chelmsford.
But he still believed the town centre was healthy and only nine per cent of shops were empty as of October, which he said was below the UK average.
The inquiry, which began on December 9, was due to finish on Wednesday but over-ran.
Planning inspector Ken Smith is due to visit the Broomhills site on January 6.
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