"Tupler developed the Tupler Technique to help women prevent or correct diastasis recti, coaching celebs like Elle Macpherson and Jewel during their pregnancies.
Pregnancy is the main cause of diastasis recti, and the majority of women — 60 percent — have one during pregnancy. The gap between the muscles, which Keller and Tupler measure in finger-widths approximate to a centimeter, can be anywhere from 2.5 cm to 10 cm in severe cases."