Your protein needs, and basically everything you eat, should fit into your dietary goals. Those goals generally revolve around your total daily calories and your macro nutrient percentages (aka: macros).
Start with one of the many calculators available on the Internet.
For a couple of weeks, religiously track everything you eat, using one of the typical calorie tracking systems.
You will probably discover that:
- You are eating too many refined carbohydrates.
- You are eating too many carbohydrates.
- You are not eating enough protein.
Regardless, you would then address your diet and figure out how to meet your dietary goals (whatever the calculator told you). If you need to supplement something, typically protein, that's where things like whey comes in.
Make sure that whatever you're doing with your diet is part of a bigger picture, don't just add "super foods", "shakes", and whatever other items without understanding how they fit into your overarching goals.
And no conversation would be complete without mentioning that strength training done right will have more pronounced fat reduction than aerobic trainingstrength training done right will have more pronounced fat reduction than aerobic training.