What are you classifying as normal? Utilizing the current rend and statistics, by 2030, more than 50% of the U.S. population will be obese - we are at nearly 40% now. So, the 'normal' people that you speak of have an issue and are unaware of it. Normal hunger regulation - is that the hunger regulation or insulin response that is giving us 7.9 million new cases of diabetes every year? The cycle of hyperglycemia post meal and rapidly decreasing levels immediately creating a 'need' or 'urge' to re-up your blood sugar - that has nothing to do with hunger regulation and everything to do with insulin regulation.
People who are normally thin and don’t give a nanosecond of thought to how much they are eating. My husband is one.