High resting heart rate?

My resting heart rate is usually in the 50s-sometimes low 60s but today has been in the 80s-90s. I’m in recovery from AN and I’ve been trying to get better about eating something when I’m supposed to (not eating as many exchanges as I should be but trying to eat something at 3 meal and 3 snack times). I’ve been in treatment since August and haven’t had more than a few days in a row below 1200 calories so I’m not worried about redeeming syndrome, I just don’t understand why my resting heart rate has been so high. My hunger cues have come back with a vengeance over the last few days and my therapist suggested I could be hyper metabolic. Is a high RHR a sign she could be right? If it’s not that then could being TOO sedentary cause this? (Today’s a snow day and I’ve been laying on the couch most of the day)