The grocer's convenience stores grew like-for-like sales ahead of its bigger supermarkets, which Mr King attributed to consumers "buying a little bit less in the weekly shop and topping up more frequently".
Mr King made his comments before David Cameron's speech to the Conservative Party conference yesterday, during which the Prime Minister decided against an initial plan to call for consumers to pay off their credit and store card debts.
Mr King said: "The other central theme of his [PM's] speech is that we need to stop doing ourselves down and talk positively about the things we are doing in the country."
The Sainsbury's boss said that a reduction in credit card spending "certainly will not help the retail part of the economy".
Sainsbury's posted a 1.1 per cent rise in like-for-like sales, excluding fuel and VAT, over the 16 weeks to 1 October, boosted by a robust performance from its non-food and convenience store division.
The UK's third largest convenience store operator grew like-for-like sales ahead of its bigger supermarket, which Mr King attributed to consumers "buying a little bit less in the weekly shop and topping up more frequently". Opening at a rate of one or two a week, Sainsbury's introduced 24 convenience stores – up to 3,000 square feet – in the quarter, taking it past 400. This helped its convenience division grow total sales by 20 per cent.
Sainsbury's also said its general merchandise and Tu clothing business continued to grow "strongly" in the quarter. For example, its back-to-school childrenswear rangedelivered 38 per cent growth over the same period last year.
Total sales at Sainsbury's rose by 7.8 per cent over the 16 weeks but it grew by a more modest 4.4 per cent when the impact of fuel is excluded.
Mr King took a swipe at Tesco's £500m price promotion that was launched last month. "It is part of the cut and thrust in the current marketplace. We can look at the last six months – it is clearly a period we have outperformed them."