Homo sapiens, as well as other primates, developed the evolutionary advantage of storing excess energy as body fat, primarily in the readily accessible visceral fat compartment when food is plentiful for use during scarcity. However, uniquely to female humans, a second transient dimorphic phenotypic change begins at menarche and is reversed by menopause. It is the diversion of visceral fat stores from the abdominal cavity to the gluteofemoral region. The evolutionary purpose for this remains unclear. The author proposes the gestational potential space hypothesis: that such fat diversion is for the reproductive purpose of increasing the potential abdominal space available for gestation and reducing the intra-abdominal pressure. This hypothesis is supported by the basic laws of physics and increased rates of maternal and fetal complications experienced by those with visceral adiposity.