GDP or gross domestic product growth fell to a three-year low of 5.7 per cent in the April-June quarter. The economy had expanded at 6.1 per cent in the March quarter and at 7.9 per cent in the April-June quarter last year. Destocking in the run-up to the July 1 launch of the goods and services tax (GST) and a lingering impact of demonetisation hurt the June quarter GDP numbers, say economists.