Amant was born as Julia Marguerite Adélaïde Valentin in the village of Pouzols, Monlet, in the French department of Haute-Loire. On 20 September 1932, she married Pierre Amant and had three children: Gabrielle, Roger, and René, the latter of whom died on Christmas Day, 2009. For 40 years the couple worked in a butchers shop. Amant retired in 1972, and was widowed in 1986.
Amant moved into a retirement home in the nearby commune of Saint-Paulien on 18 November 1999. At the time of her 110th birthday, she had six grandchildren and nine great-grandchildren. She died on 30 October 2021 at the age of 110 years, 130 days. Four days prior, her son Roger had died aged 82.