Protein doesnt cause obesity
eating large amounts of mono or disaccharides, or fat does.
For this reason, protein shakes are actually excellent. They contain very little sugar and fat. This makes it easy to controll your intake.
If you cant cook, just eat the right dosage of complex carbs during the day (oats, grain, bread, rice, pasta), with as little fat as possible, and add a shake for the protein.
its what i did when i was on holyday in march, a month before my competition. bacon and eggs breakfast, shake after, bread with bacon at noon, 2 shakes in the afternoon, something meaty for dinner, and a shake before going to sleep.
Its so easy