What I found works for me is to make a lifestyle change rather than go on a diet. I also try to keep track of the amount of calories I take in on a daily basis. Along with a
little exercise, this seems to be the key for me. With regards to the cholesterol, try to watch the bad fats and substitute good fats. Bad fats being saturated fats, trans fats, etc. Good fats come in olives, olive oils, avocados, etc. Fat in either form does have more calories than carbs or protein, so if trying to lose weight you'll need to be careful even with the good fats. Not sure why your doc suggested to lay off the protein.
Don't kick yourself if you fail. Just get back up on your horse and try again. Two steps forward, one step back, is acceptable as long as you continue your forward momentum. Ultimately it is up to you and shear will power. You and you alone control what you put in your mouth. It can be tough, but it is worth it. Good luck!