Nutrition is complicated. So is gravity.
We don’t need to know exactly how gravity works. Not most of us anyways.
For our purposes (surviving) we, the non-physicists, need not know too much about intricacies of gravity.
Do I really need to know how to calculate how much force I’ll hit the ground with if I fall off a two story building? Not really. I only need to understand the outcome.
Nutrition is the same.
Biology, like any hard science, is damn complicated. We don’t know everything about it yet, and probably never will.
To improve our health, we can get really really far with this statement:
Eat more vegetables.
Most people navigate gravity well enough without a physics degree.
Nobody trips and falls and is then surprised they don’t start floating.
See where I’m going with this? I know I ought to eat more vegetables. You know this too, so don’t act like you don’t. You’re smarter than that.
We can go pretty deep down the rabbit hole of nutrition. We can pour over minutia and every teency little detail. And there are times where small details can be helpful. However, if we just want to fit into an old pair of jeans again, such specificity is unnecessary.
A skateboarder does not need to understand quantum mechanics to do shit like this.