[SuchAnonMuchWow]

Personally, I enable battery saving mode: it prevent any app from using data in the background, so whatsapp won't synchronize with its servers at all unless the app is open.

The drawback is that this behavior can not be enabled on a per-app basis: either all app synchronize, or none. So I don't have new emails either unless explicitly enabled, or any other similar app. The only thing that still works and notify without requiring the app to be open are text messages and phone calls.

I consider that to be a feature, but other might not.