A few minutes of scrolling a fitness model's photos leaves women feeling worse about their own bodies. Researchers have tested it, and it goes a long way toward explaining how a regular mom selling a 30-day challenge can outsell accounts with millions of followers. Flinders University ran the experiment in 2015. They sat 130 women in front of an iPad showing either Instagram fitspiration posts or travel photos. The women who saw the fitness posts came out in a worse mood and less happy with…