Is it normal to hate people who assume!

Okay so I am overweight I'm 200lbs and I've been trying to lose weight for a long time now. But it PISSES me off how people who are at a 'healthy weight' (though I don't believe there's a healthy weight. I think there a heathy you, you can be 115lbs and eat as much crap as you want and not gain an ounce and be 200lbs and work your ass off and nothing happens. To me it's more about health than weight) try and tell me how I should lose weight. I know almost everything there is to know about losing weight. It isn't the knowledge it's the state of mind. I know I need to work out minimum 3 days a week for a half hour and I know you can't eat under 1200 and shouldn't eat over 2500 on average. I find it annoying how people assume because you are larger you don't know how to lose weight! Actually I really just don't like people who assume things they know nothing about.