Thinning Xcode 7 iTunes Connect App

Question

I am using Xcode 7.0.1 (7A1001) and noticed that sending my application now goes through the Thinning App stage and the folder is created using a large .ipa for different devices supported by our application.

When I download the app from iTunes Connect Test Flight for testing, I don’t see a decrease in size. Can someone shed some light on whether the size of the application should be smaller? Am I doing something wrong in the configuration or will it only be less when downloading from the actual App Store ?

Thanks!