if this actually worked, why so so many dieters fail? if this works so well, someone could make a diet program out of it, it would be super-effective and would sell billions. obviously easier said than done.

high nutrition, low cal foods (relatively speaking)

this is sorta contradictory. calories are nutrition.

From what I gather, dieters frequently count calories rather than tracking nutrients. If you are already deficient and try to limit your intake of food and it worsens your deficiency, at some point you are likely to spaz and stuff your face in desperation.

physics work

therefore diets work

Except there are some weird feedback loops in the body, such as restricting calories leading to reduced calorie consumption, leading to less weight loss than expected.

no. literally conservation of energy. humans cannot beak the laws of nature. calories in > calories out