More likely is that the OP just isn't doing enough. Running 25 miles a week is enough to bring about significant benefits in health and fitness along with moderate weight control benefits. 25 miles a month is just a waste. Going up from 1-2x per week to 3-4x makes a huge difference.

Most likely is that it's a dietary issue. While living in Asia, I knew many, many non-exercising people at healthy weight levels just because they didn't overeat like Americans tend to. The OP probably doesn't eat like them.

What I was saying was that merely building muscle doesn't do much in terms of cutting down body fat. Muscle burns calories, but people with more muscle also tend to eat more calories. This is even true of people who have extraordinary quantities of muscle.

Cardio, on the other hand, only works that way up to a point. People who do a bit of running also tend to compensate by eating more. However, after a certain level of volume, cardio starts to suppress the appetite to about what's needed to maintain the workload. This is probably why I've never seen anyone, including myself, manage to keep the weight on after getting over about 70 miles/week (about the level of an ambitious high school cross-country runner).