In 1944 his mother had been a relatively svelte one hundred and eighty pounds.
-- Stephen King, It: A Novel
“When I walk under one of the pathway lamps and look down you can indeed see the silhouette of my body which doesn’t look quite as svelte and hourglassy as I believe it did just an hour ago when I was admiring myself in the mirror.
-- Terry McMillan, How Stella Got Her Groove Back
Svelte enters English in 1800s from the French, and originally derives from the Latin verb exvellere, "to stretch out."