To lose weight or not

Recently my three roommates have been losing weight by running , going on a diet or doing exercises.They always complain about their 'fat legs','fat arms' , 'fat waist ' , but in my opinion, they all have normal figures !! At least, they are slimmer than I am, but I never feel that I'm very fat and that I should lose my weight,and so the fact is according to the standard.
On the other Hand, a slimmer figure is more beautiful in the same clothes.Now the question is :Do I need to lose weight or not???
*instead of "Do I need to lose weight or not??" you could use "should I lose my weight? or Should I try loosing my my weight??".

Hi my friends, I can only use simple sentences to express myself, if you have a better structure ,please give me a hand, thank you very much!! have a good day (^_^)