I have a coworker who runs marathons. Took it up in her early forties. She weighed 170 pounds at the time (5'6"), having dieted down from about 230 pounds. She gained weight after she started running. She got back up to about 200 pounds before she reined in her diet again. She's back down to about 180 now, I think.

To me she's Exhibit A in response to the argument that exercise causes weight loss. I suppose an advocate of CICO would say she just eats too much. I'd argue that if she starved herself, she wouldn't be able to run 26.2 miles in one go.