Personal experience, I was running for miles for the last couple of years and still piling it on. Back to weights now 2 days per week and running one, and am burning it off surprisingly rapidly. Note, though, that I wouldn't be exactly beginner level when it comes to weights.
I don't know what your pace was or whether "for miles" means 2 miles or 10. But there are plenty of apps for iOS and Android that will tell you how many calories you burned on your runs, and if it was multiple miles and you were maintaining a decent pace, you probably burned many more calories on those runs than you do lifting.
The likely reasons you kept gaining weight while running, pick one or multiple:
- Not running as often as you lift, so the total calories burned per week (or month) was lower.
- Running too slowly so that your heart rate didn't get up to the point where you were really working.
- Ramping up your carb intake, whether consciously or subconsciously this is really common when people start running -- your body starts craving carbs. Which then results in a calorie increase, which is the real problem (not carbs themselves.)
- Policing your eating better while lifting.
Ultimately if you want to lose weight you have to not only exercise but also keep your daily calorie budget at a deficit. People who have trouble losing weight usually fail at the latter one.
I lost a lot of muscle mass, and I just wasn't running 'enough' to be burning all the fat off. I think the main problem was the muscle mass, which eats food even when I am sitting on the couch.
