Megan Markoff , director of nutrition at coaching company Pallas , was scrolling Instagram when she saw a controversial post claiming “running made me fat.” She grabbed her phone and recorded a response video that later went viral, rebutting the statement. “I see this all the time. What usually happens is a mismatch between training and nutrition,” Markoff said to the camera . Across social media, influencers are increasingly warning that long-distance running leads to weight gain. “I didn’t even understand how prominently this narrative was getting pushed on social media until a new client told me about it,” Markoff tells Runner’s World. But the reality is nuanced. While it’s perfectly normal—and often beneficial—to gain some weight during a half or full marathon training cycle , Markoff says social media often oversimplifies and misrepresents what’s actually happening in the body.…