I have made the very same experiences. The last fatty looked genuinely shocked when I explained of how counting calories, but eating filling food (eggs, beans, potatoes...) is the key and I told him what I usually eat (easily more than a whole kilogram each day) "And how am I supposed to feel stuffed!????!" Since then I never bring up nutrition and weight loss talks with fatties anymore and decline to join in whenever this topic arises. Don't feed the askholes!