How come fat and fried foods are bad for us?

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Everyone says the biggest part of your calorie intake has to be from carbohydrates (focusing on the grains) and the fat has to be reduced to minimum. Could that even be said as the holy grail for healthiness and weight loss? Actually I think its quite the opposite. And I'm focusing only on eating without counting calories and actually letting the brain tell you how much and when to eat. No matter how much fat you eat that wouldn't spike your blood sugar and will keep its levels stable for the next hours, because fat is metabolized slower than all the whole-grain products, not to mention the refined ones. So then if a person needs a certain amount of calories for the day, instead of eating 1000-1200 grams of chicken and double or even triple his protein requirement for the day, he could rather fry 500 grams of chicken and get his calories and protein just at maintenance levels. What is wrong with that?