If insulin is why we are fat, how does he explain all of Asia? For centuries they have lived off primarily rice or in some parts of Japan sweet potato, they are the leanest in world and don't say genetics.
many different reasons but the main ones would be lifestyle - specially activity levels
you ever see those videos when people go over to china and the old people all in a formation doing tai chi? They are exercising , they move , they understand the importance
they are hunter gatherers for the most part still, you ever worked a rice field ? also just look at Chinas work ethic as a whole - you drop a dime in front of them they will work, asia is also a place full of slave labor because they aren't lazy people - they work , its wired into them
the western world is made, since school, to feel we are better than most countries, without even BEING there
everyone knows for the most part of familiar with cannabis cultivation - the methods and such - but its like ANY plant you experience a harvest, nutrients a plant need , water, temp, clean air - its a living thing
muscle tissue is living so you must support that as well in the same way as I mentioned above - no different - you want big ass stank ass plants add fertilizers -
you want a big oversized human - add fertilizers
but when you want someone to get fat, as we do with lets say cattle, you confine them into large populations , feed them food that will purposely fatten them (refined carbs) in the cows case corn meal, that's it -- they have to pump them full of antibiotics because of the confined space - same as us
think of societies closest to a caveman/hunter gatherers - they are 'lean' because their lives closely resemble that of our ancestors
we are at least 2000 years old for argument - you think we had iphones and shit 300years ago ?? but there were vegetables like rice and sweet potatoes as you mentioned ? so why would someone eat McDonalds and sugar all day and expect to look like their ancient self ?