Our typical Western diet is full of inflammatory fats - saturated fats trans fats too many omega-6 inflammatory processed vegetable oils like soy and corn oils. These increase IGF-1 and stimulate pimple follicles.
The term 'the American Left' is as near to being meaningless or nonsensical as any term could really be in politics. It isn't really a force in politics anymore. And it would do well to ask itself why that is.