Why should we limit fats sugar and salt in our diet

We should limit fat in our diet because not all fats are good for your body some are very dangerous
we should limit sugar in our diet because sugar as most people know is bad for your teeth and body. Too much sugar in your body could lead to a blood sugar spike and dangerous sugar drop ... you could pass out or throw up.
we should limit salt in our diet because to much salt in your body can lead to dehydration.