>There is a lot of evidence that obesity is not hereditary/predetermined, but is a choice (or a consequence of a weak mind/bad incentives).
There is a lot of evidence that obesity is mostly hereditary/predetermined and not a choice. That's the great thing in this area of science: Everybody proofs everything all the time. No one's wiser.
> To take it to the extreme, there were no fat people in Auschwitz. That is not to say that it was good in any way and that people should starve, but just that it is not impossible to be normal for anyone, you just have to try.
So, you state that one can be lean by being forcefully starved (Auschwitz), then state that you don't think this is a good idea and then state "but it is not impossible to be normal for anyone" - well: You didn't provide an example for "normal". This people in Auschwitz were starving. Food-related diseases (and all other diseases) were on an all-time high. People were dying all the time. This is not an example of "normal", this is an example that the human body is able to withstand many, many forms of abuse until it breaks.
You would help this discussion if you were able to provide examples of big groups of obese people (there are always outliers) which were able to get lean without starving (starving is really, really bad for your body). Thanks.
edit: I've missed the part about Vietnam/Africa before. If you didn't see any fat people in Vietnam then you probably didn't look hard enough. I was there and I've seen them. Africa: Documentaries on Africa usually focus on the really poor parts of Africa. People starve there too, so: See above. (Also: There is the case of hunger obesity where you get really obese because or starvation. Try Google, but beware of shocking results)