Chemo works. Look at Lance.
ANY additional weight kills your times at distances over 10 k. Regardless of height.
But like the rest have said you WILL NOT gain weight/muscle from lifting weights unless you eat more. Not even if you take certain, non-aromatizing steroids.
And more power equals more speed.
stop using steroids?
Eat less. Run more.
Junk Master wrote:
ANY additional weight kills your times at distances over 10 k. Regardless of height.
Of course it's not necessarily easy to figure out what counts as "additional". Everyone gets to a point where losing more weight would be counter-productive. For some putting on a bit of muscle in the right place might help. Elite marathoners are not necessarily super-skinny. For example if wikipedia is correct about his height and weight then Geb has a BMI of 20.6 which is not really that low.