Green’s Dictionary of Slang

(US) to diet.

[1870		Charleston Dly News (SC) 26 Jan. 1/6: The Banting system of diet is explained].
[1874		‘Old Calabar’ Won in a Canter I 43: Banting, Tim, Banting. No bread, no butter, no sugar, no beer, no saccharine matter of any sort; plenty of meat, biscuits, toast, claret and seltzer-water. That is my diet’].
1890		Dead Bird (Sydney) 20 Dec. 2/4: Joethorpe has been ‘banting’ of late and is confident of reducing his weight by a couple of stone before Easter.
1904		Pittsburgh Press (PA) Mag. 6 Nov. 43/1: He had to bant, to diet, to exercise, to do anything and evertyhing to keep himself from growing fat.
1909		J. Ware Passing Eng. of the Victorian Era.
1909		Goodwin’s Wkly (Salt Lake City, UT) 5 June 9/2: Bant, bant, bant! Oh, Fashion, at thy decree [...] she bravely starves to get slim.
1912		A. Brazil Fourth Form Friendship 71: As for Lorna, she's been banting in preparation; she hardly took any dinner’.
1920		Ade Hand-made Fables 35: They could not Bant fast enough to keep up with her.
1926		Van Vechten Nigger Heaven 158: You’d better bant, Lutie, suggested Dr. Lister.