My typical diet is oatmeal in the morning, turkey/tomato sandwich with an apple for lunch, and dinner (meat, vegetable, starch). I go to a boxing gym 3 nights a week, would it be a good thing to drink 24 grams of whey protein in the afternoon before going to the gym? Not on the off days of course.
AnthonL - It is always a great idea to add extra protein to aid in tissue repair. Depending on your body size I would recommend one gram per pound of body weight.
More importantly (relative to putting on body fat) would be your overall caloric consumption. If you are taking in too many calories (compared to how many your burning) it doesn't matter whether they are from whey protein or sugar, you will put on body fat. You should find out your overall caloric consumption and compare that to your basic metabolic rate and factor in your workouts. get a total number of calories you can comfortable consume and then build your diet around that number, with at least 4 calorically even meals and don't eat too close to bed time.