I came into weight training from a background of competitive distance running...lots of structured workouts, sequenced races, running and duathlons (they were called biathlons back ten) and was very successful runner. However, I shudder when I look at pictures of myself back then. I was a twig.
Now, I am willing to wager, I am still a nutty runner compared to most on realjock...still managing abotu 50 miles per week, with no injuries...no arthritis...nada. But I have also worked in lots of weight training, comparatively (about 5 hr per week).
I'm not advocating the running. It's just something I do. But it burns calories about as efficiently as any activity, minute for minute. By the way, the running I am talking about is NOT on treadmills or other machines. No matter what the dials say, you are NOT running, say, a six minute per mile pace on such devices. At least you're not running that equivalent to what you could do even on a flat road...because even on a flat road there are irregularities and hard pavement which is not "giving" at all. Oops...that's a tangent. Sorry.
Running works well when intermixed with weight training, if you like running.