I love Beth Ditto - let's talk about sex baby

Not if you're an eskimo/Inuit? Its genetically bred out, the possibility of being "skinny". There would be no fat to keep the inner organs warm in the freezing temperatures, and the person unfortunate to be born skinny, would die of "exposure".

That said, Tonga and Fiji are warm climates, but the indigenous population are large, and carry a greater fat store than many other countries' average populations.
Its again, genetic.

The Ectomorph - skinny, fast burn metabolism, (eat all they want and don't gain weight)
The Mesomorph - average to muscular structure, and naturally healthy and strong shape
The Endomorph - fat/obese, slow burn metabolism, stores more fat from each meal than other body types

These are all genetic models that we all fall into. But some do straddle two body types. But any Ectomorph, can never change into an Endomorph and vice-versa.
I have mentioned these before in another thread, but I can't find it to make a link.

Being fat, can easily be unhealthy, but a fat person can be healthy also.

I think that 'ectomorph, endomorph and mesomorph' stuff has been pretty much discredited.