LayZ boy has always needed to compete with me

LayZ boy, a male, tries to compete with me, a female, all the time.

He seems to think that he needs to compare his male torso with my female torso and tell me that he has the better body because I don't have a 6-pack stomach, yet neither does he. He is male and is supposed to have less body fat than me, a female, but he cant seem to understand that concept of reality. Most women (unless they are athletes or body builders) wont have a 6-pack in their abdominal area and most women don't want to. It is enough to have a flat stomach and look good in your clothes.

The other day LayZ boy was in the hallway telling me that I don't have muscles in my stomach like has on his stomach. He's never felt my stomach so how would be know anyway?  And I do have toned muscles in my abdominal area, I just have a little bit of a convex shape, very female and womanly, but not overly so. When I wear anything tight, it looks like I have a flat stomach.

Anyway, LayZ boy lifted up his top to show me his abdomen and told me that he had a better body and that I was obese. Yes, sure, I am a size 10-12 (USA 6-8), of course, I am obese! What an idiot he is! And then he starts telling me that I have to watch what I eat because my waist is obviously bigger than 80cm (which is a risk factor for diabetes and heart disease) and told me that I am a fat, obese loser. I just looked at him and told him he was an idiot and walked away to my bedroom and locked the door.

LayZ boy cant seem to comprehend that he is a male and I am female and that we don't have the same bodies to compare - it is ludicrous to do so. He obviously doesn't think too highly of himself to have to compare his body to a woman's in order to come out the winner. What idiocy I have to put up with. Needless to say, this is one of the many reasons I do not engage in conversation with him because he has no ability to be normal to me.
First of all, he has never measured my waist and secondly my waist is 75cm - I measured it about a week ago, so he knows nothing and is just spouting total boorish nonsense, as usual. He's just saying these things to bait me, upset and antagonise me. He's been doing that since we were children and wont stop now that he's an adult. He is a total and utter moron with no brains to call his own.