Does taking protein shake helps to lose weight or will it actually makes one gain instead? Without doing any strength exercises?

I'm asking out of curiosity only.

Well, ya I didn't think that just taking protein shakes alone will help to lose weight. My bro has this thinking though. He is now starting on protein shakes (with milk summore!) and only doing 30mins cardio once a week, which I told him isn't enuff. He is very stubborn and kept thinking that protein shakes will help him lose weight just because a friend advised him to do so. He is taking it as one meal replacement which I guess isn't that bad but still, I don't see how it will help him lose weight without doing more exercise along with drinking the shakes.