There were some posts some time ago regarding loss of appetite while backpacking/climbing at altitude. I've experienced the same, was not able to figure out after hiking all day, every day, in difficult backcountry terrain (off trail navigation) in the High Sierras why I wasn't tearing into my dinner, or breakfast, or snacks for that matter. I felt like I had to nearly force my food down. I never got enough calories, actually jettisoned about 3 days worth of food on our last day. A little research produced the following answer. Hope it offers some help; it did for me: https://bit.ly/3yKsT9s