I'm not going to argue over a diet now, because I'm not a nutritionist (thank god for that) and *my* diet qualifies as "very poor" because I'm mostly a lazy bast*rd. However, we are the same age and I weight 65 to 70 kg (depending on how much I exercise) for 175 cm. A bit on the thin side probably, blame it on me being lazy and/or too busy, I tend to skip meals (and I do exercise quite a bit).
Anyway, my point was that your so-called facts are mostly wrong (except for the bit about the gastric band, and also the fact that trash food is heavily advertized, easily available, and appetent). My detailed rebuttal -which was sniped by the moderation team, probably for being uselessely long and boring- was a scientific (physiology and biochemistry) one. I'm not going to retype it because it would take quite some time, it would probably be killed again, and I don't really give a fuck anyway -and I'd bet you don't, either.
Your weight loss on a low-carb diet can probably be explained by the fact that your energy intake was adjusted to fit (or be a bit below) your energetic expenses, and not by the "low carb" part. These diets -in my very modest opinion- are mostly trends, but again, I might know a thing or two about normal human physiology (my paycheck would tend to say so), but I'm in no way a specialist in obese people's metabolism, so I might very well be mistaken. Extreme cases might, after all, call for extreme measures. Understand me well: I still don't believe in these trendy diets, but I have no way of proving they are rubbish. Put in another way, your "facts" were scientifically wrong so you certainly failed to prove that your diet has a scientific basis, however, there still might be one. I doubt it though.
In short, whatever works for you is probably good, and, as a psychologeek friend of mine would put it, "Obesity starts in the head" (yeah, he's a strange guy).
Be careful not to be abused by charlatans and swindlers. They abund. "Rip off the fatso" is one of the most lucrative occupation in western countries since "investment bankers" is getting risky. If the "facts" you presented here were given to you by a "nutritionist", I strongly suggest you kicked his/her probably skinny arse and find a real one.