parents dieting

Something that i've noticed throughout my parents diet or mostly my dad's how they think about food and weight. They talk about it a lot and are very conscious about what they put in their mouths but mindset to cut back healthily is somewhat confusing to me. How can you diet but still be in a healthy mindset? It fascinates me to be quite honest. they still have a healthy amount of calories but it's in healthy foods and in moderation. My dad said awhile ago that he still has 600-900 calories to save for dinner and that's just baffling to me because that could easily be my breakfast, lunch and a snack combined. He told me his goal is to lose 2 pounds per week and i replied surprised "That's it?!" keep in mind that's a HEALTHY amount to lose a week. A week in a half so far on their diet i've realized how abnormal my thoughts and behaviors about food really are. An acceptable amount for me to lose in a week is a pound or a pound a half a day. How can you consciously change your eating habits without disregarding your health? It's really interesting to me.

I think anyone with disordered eating/eating disorder would agree with me. Am i the only one who feels this way.