I'm just a patient w/Atrial fibrillation so I can't really answer your initial question. However, YES, I have read of anorexia causing cardiac arrhythmias and cardiac insult.
Just to ease your mind tho why not ask this same question in the Ask The Expert Heart forum here?
What is your resting HR now? Don't take too much from any one reading. It may be you were excited by the new procedures you councilor was giving you.
A HR of 120, even at rest, is a non-emergency. But, a HR that is always over 100 at rest should be checked by a cardiologist, I believe.
Again, what is your HR when you are alone and truly at rest, physically and emotionally. You mention 80+ being more normal. To which I say 80+ is a bit high in my book. My resting HR is about 80, but I suffer from atrial fibrillation.
Let me just say congratulations to you for starting to recover from anorexia. :)
Anorexia is a very scary ailment. It originates in the mind but it affects the body too, and it can be one of the most difficult things to overcome. I know, because I have been there. My case wasn't as extreme as many, but I have restricted my calories and lost a lot of weight in a short amount of time. In fact, it was during that period that my heart issues started. I would get flutters and arrhthymias and all sorts of scary stuff. It was during recovery, however, that my troubles were at their worst. My heart would start racing for no reason, often several times a day. Like you, my resting heart rate was also higher than it should have been. I was terrified to the point where I barely wanted to get out of bed. It is only now that I have a better idea of what was going on that I am able to relax. See, after eating so little for so long, your metabolism slows down to a crawl, and your heart rate slows with it. When you start eating more, your body is forced to wake up and start digesting, and the shock to your system causes an increase in heart rate that may manifest itself over a long period of time.
Luckily, our bodies and our hearts are tough, and are able to adjust. It will take time, but I'll bet that after you're fully recovered, your heart rate will slow and your health will be better than ever. Keep eating, and believe in the power of your body to be healthy once more. Make sure you aim to reach a healthy weight: aim for a body mass index of 20 or higher. Talk to your doctor about a recovery plan, if you are not sure how to go about it on your own. Love your body, take time to appreciate it, and you'll feel better soon.
If you want to talk, you're welcome to send me a message anytime!
All the answers others gave you above are good ones, Bran_Bran. 60-100 is a "textbook normal" heart rate. 120 is only slightly higher than that and can occur with activity (even just talking or moving in the chair), fever, nervousness and countless other things. (Even hyperventilating---breathing too fast and/or too deeply while learning the breathing techniques could affect heart rate/pulse.) You are young with few risk factors for dysrhythmias (abnormal heart rhythms) other that the anorexia which can cause a loss of potassium or imbalance of other minerals and blood chemicals leading to dysrhythmias. You're getting a handle on that, though, so the heart rate was likely not caused by that. Atrial fib results in a heart rate that is usually fast when untreated but can be slow; it's always irregular, however. A single, isolated measurement of pulse or blood pressure isn't very informative or important as a rule; rather, it's the trends over time that count. I think the most likely cause of your increased heart rate was nervousness. It's likely that no treatment is needed---just let your doctor know if you have repeated episodes of your pulse being higher than normal or if you have dizziness/weakness/palpitations (though palpitations in a young, healthy person are usually not serious either). I'm so proud of you for making progress in your battle against anorexia. You've made so much progress since we started chatting nearly 1-1/2 years ago. I hope you're as proud of yourself as I am of you. Keep up the good work!
I came here looking for the same answer. My calm heart ratr has been 120 bpm. I can get exhausted after 2 minutes of intense running and 10 minutes of light running and my heart jumps to around 200 bpm