another factor heard from... a major metabolic regulating hormone, thyroxine, trumps diet every time. It also explains many of the other problems you encountered. The dosage of your medication regulates your basal metabolism much as a pacemaker regulates the heartbeat... you can't exceed your "cap". Dieting works on the assumption that when calories are restricted, the body will alter its metabolism to utilize stored calories (aka fats & glycogen) to fuel the body. That's what is meant by the phrase "burning off the fat"... it is metabolized/burned.

The main reason why iodine is added to table salt is to ensure that enough is ingested with meals to provide an often missing ingredient the thyroid needs to make the hormone.

Another kicker is that there are more than one type of fat stored in the body and these are metabolized somewhat differently. Starvation & malnutrition have been powerful selectors over the generations, so it should not be too surprising to find that those organisms that are still around have developed a variety of ways to stay alive & leave descendents.