Method for forming a packaging (2) from a container (1) that has a body (5), a neck (8), and a bottom (6), the container (1) having a deformable zone (15) with an extended configuration in which the zone (15) projects toward the outside of the container (1), with a retracted configuration in which the zone (15) projects toward the inside of the container (1), with this method including the following operations: filling the container (1) with a hot product; closing in an airtight manner the thus filled container (1); measuring the temperature of the stoppered container (1); comparing the measured temperature to a preset threshold value; if the measured temperature is less than or equal to the threshold value, moving the deformable zone (15) back toward its retracted position.