They may be being blunt, but it sounds like its crucial in this situation to be in shape. Otherwise if they hadn't said anything and you ended up going on this hike that ends up being terrible for you and in turn for your friends if you can't keep up, thats not really good is it? Nothing wrong with being out of shape, but your friends are doing you a favor by being honest. Going on a long hike is serious business physically. It sounds like your friend was being honest in the nicest way she could. I would take it as constructive criticism. Hit the gym, get serious about being healthier and more in shape, and plan on going hiking the next time. Unless you feel like you can work out enough before this one in order to take it on. I'm 5'7 and 165 pounds and hiking for several hours isn't exactly easy, especially six, depending on elevation, uphill or downhill. But back to your question. This isn't some simple outing, its a six hour hike so I don't think your friends were exactly wrong for being up front before you get yourself into something you might wish you hadn't. Good luck either way ☺