I'm in no place to say yes/no in terms of whether it's going to be good for your health, but:
I decided in February 2012 that I wanted to take part in the Brighton marathon, which was two months away
At the time, I was overweight: 6' 3" and 16st 7. However, I was only 23 so relatively young.
I ran up to 5 times a week, very slowly (11 min mile), and gradually built my distance up from 2 miles. At first, I was struggling after the first mile.
Two months later I'd increased my distance to 16 miles.
On the day, I managed 19 miles before I had to give in and walk the remainder. At the 13 mile point I felt perfectly fine and very strong.
I probably went about it all the wrong way and did myself no good but for me, a half marathon would have been a breeze. There are of course a number of variants such as age, gender and weight, so for you it could be a completely different story!
The reason I don't think BMI is always a great indicator of how your body type affects athletic performance, is because I personally know people who have a BMI of 25 or above (overweight) but win races and look to be prime phisical specimens (no fat or excess muscle). I wasn't saying ignore your BMI, that would be nonsensical, by saying don't take "too much" stock from it, I was simply suggesting that a high number may not necessarily mean that you're not built for running (although it often does).
I only mentioned picking up a weight because it can better put things into perspective. You seem to think I'm suggesting that me running = Millsy running + 35kg which is not the case. The only message I was tyring to relay was that more weight generally equals more energy expended, and although height defititely comes into it to some extent, there seems to be no scienfic research to suggest by how much?
If you can direct me to any such article, or answer on a scientific or evidential basis then please do?
My step-father has a BMI of 25 - if he was a couple of pounds heavier he would be classed as overweight even though to look at him, he's thin and toned.
When I say heavy, I purely refer to how much weight you have to carry with you. If you do the maths, I weigh around 35kg more than you which is quite a lot (go to the gym and pick up the 34/36kg dumbell) Based on that logic, I think I'm fairly safe to assume that you'll propably exert less energy than me when completing a long distance run at an equal pace.
Obviously there are loads of other factors to consider though - I think if research was undertaken to measure the effects of height, weight, age, BMI, etc, the results would be fascinating.
Best of luck with that, I'm sure it will be a breeze for you! When I started running, I found that my 5k time tumbled from 30 min to 25 min very quickly. Turning 25 min into 20 min is proving to be a much hard challenge though.