The details of the diet But what will happen

If you don't mind losing an inch or two you can easily limit yourself to 3 meals a day. Just (for the first few weeks) drink your whey in place of other other 3 meals. Protein=girth=large bulk muscles. If you take protein out of the picture then BAM no muscle. Also exercise is important. You have to ask yourself if you want to be bodybuilt or lean and mean. You can easily take off diet and add on working out to keep your girth up, which is totally acceptable.

Just remember not to stop all at once. Go down by 2-5 g of protein a day until you're about at 15 g. This is healthy and will maintain your muscle mass. Also eat more carbs as a result of this protein exclusion. The carbs will give you more energy at the gym and will be burnt right off so its not a problem.

The little things add up. You may have to give up a little muscle but (if your persistent and want to keep your body the way it is) you can do it. Just keep the balance. Take care of yourself.