Research firm Kantar Worldpanel reported that total category sales climbed by 3.6% year on year during the 12 weeks running up to April 17.
But the category's overall expansion lagged behind a 4.3% rise in inflation, meaning trading conditions are still mixed overall.
More specifically, Aldi enjoyed a 15% surge on an annual basis, and Lidl experienced a 14.7% lift, boosting the two organisations' market shares to 3.3% and 2.6% respectively.
Tesco had a 0.1% share decline, to 30.4%, as Asda contracted 0.2%, to 17.4%, and Sainsbury's slipped 0.1% to 16.3%.
"Major share growth remains elusive for the top four retailers this period with only Morrisons outperforming the market," Kantar's study argued.
However, as high-end operator Waitrose logged an improvement from 4.1% to 4.3% across the timeframe assessed, trends more complex than cost-cutting by consumers appear to be at work.
"This trend is not a re-run of 2008," Edward Garner, communications director at Kantar Worldpanel, said.
"But while their basket sizes remain relatively small, there is no doubt Aldi and Lidl are taking a larger portion of shoppers' spending."
Data sourced from Kantar Worldpanel; additional content by Warc staff