This is the sort of research that gets straight teenaged boys excited about science.
Keep in mind this is a single study and that it doesn't take into account many potentially confounding variables. From Counsel and Heal (and reported all over the place):
Women have long been told that a good bra can help support the chest, relieve back pain and prevent sagging. However, a new 15-year French study reveals the opposite: bras do little to reduce back pain and, over time, they can actually make breasts sag even more.
Researcher Prof. Jean-Denis Rouillon, a sports science expert from the University of Besançon in eastern France claims that "bras are a false necessity," according to The Local.
"Medically, physiologically, anatomically - breasts gain no benefit from being denied gravity," said Rouillon. "On the contrary, they get saggier with a bra."
Rouillon and his team spent years measuring the changes in the breasts of 330 women using a simple slide rule and caliper at the Centre Hospitalier Universitaire (University Hospital) in Besançon, where he carried out his research.
He found that no evidence that bras helped ease back pain. Instead, he found that the chest supports could even add to the problem.
According to The Connexion, the findings suggest that breasts would gain more tone and support themselves if no bra was used. Researchers explain that bras limit the growth of supporting breast tissues, leaving the breast to wither and degrade more quickly.
The study found that women who took off their bras for good experienced a 7mm lift in their nipples each year they didn't wear a bra. Researchers also found that bra-less women developed firmer breasts and saw their stretch marks fade.
Some of the women who took part in Rouillon's study told France Info that not wearing a bra helped ease their back pains.
Capucine, a 28-year-old participant in Rouillon's study, swears by the results and hasn't worn a bra for two years.
"There are multiple benefits: I breathe more easily, I carry myself better, and I have less back pain," Capucine said, according to France Info.
However, Rouillon says the findings do not mean all women should throw away their bras.
"It would be dangerous to advise all women to stop wearing their soutien-gorge as the women involved were not a representative sample of the population," Rouillon said, according to The Connexion.
While his initial results "validated the hypothesis that the bra is a false 'need'," he says that women who have been wearing bras for a long time would not gain any benefit from stopping now.