Why is my News & Weather app using so much data (and battery)?

I'm running Android 6.0 on an HTC M9. In the last 13 days, my News & Weather app has used 1.37GB of data. In that same period, Google Play Store used 1.22GB. For a few weeks now I have had severe battery issues (from around 36 hours of light use down to 4 hours - 5 if I leave it on my desk and do nothing), and I'm now assuming that this is the cause. I don't know why a news app would use so much data, and it's all background data which makes it even more shady. Has anybody experience their News & Weather app going out of control like this, and does anybody know how to stop it?