Go to your doctor. First, he/she will help look at the reasons why. More importantly, your eating disorder needs some help. It's not healthy, and can really, really mess your metabolism up for years, if you don't get it checked asap!
If you have done alot of exercise over a sustained period, your heart rate being that low is probably nothing to worry about. The heart gets stronger and beats more efficiently the more exercise you do. I would make an appointment to see your GP, make sure you drink plenty of water.
As said go and see a GP. I have low blood pressure due to various medications and often lose my footing when I get up and hold on to the walls!
If you find anything like dizziness etc... is a problem, caffeine dilates your blood vessels which can help a lot. You can buy pure caffeine tablets or pro plus which you can halve/quarter and just take a steady dose throughout the day.
Other than that, see your GP. Fortunately low blood pressure is no way near as dangerous as high blood pressure!
I got it checked and I have right branch bundle block but apparently a lot of people can have this and exhibit no symptoms. It is not necessarily indicative of a problem. And in my case it isnt.
I had a full work up on Harley street (my father works there handy huh? ) ECG, Echo and Full blood count. And by all accounts my fitness seems to be higher than most peoples. They also said that the low BP could be because of my low body weight and also dehydration might be a factor too.
I will go back in a couple of weeks to check everything is still ok.