Imho, it makes NO sense to change the original protocol. If your dose is right, you are not hungry on 500kcal. It is not a hardship at all. PLUS, you aren't really on 500kcal since with hcg, your body mobilizes all the additional energy it needs from the fat cells.
Doctors are delusional at times, because they still have a huge "starvation diet" sign blinking above their head. That would mean the body goes into starvation mode on 500kcal, with the metabolism slowing and the body holding on to any fat it can. Which does not happen with HCG. If a doctor cannot disregard his definition of a "healthy" standard American diet, or cannot disregard his preconceived notion of a starvation diet, he just shouldn't offer HCG.