Everything can be told without agression, even seriouse things

So! i have realized that one fo my family members seems to think being aggressive, speaking like i was a brat to them and widening their eyes like i told them god doesn't exist is a way of criticizing.

My dude... you can tell me i should keep a watch on my weight and that i went overboard with the chocolate our distant relative bought us (since we don't buy chocolate in general) without perceiving me like i killed our family just because i said "Why is Mom suddenly obsessed with my weight?", there is no need to portray me like I'm some kid throwing a temper tantrum because my relative wants me to be healthy. 

The worst part is that if you tell them they can tell you that you have gone overboard without the aggression, they would simply tell you they weren't, and when you point out their clear tone, facial expression and/or body language portrays them as angry they get more annoyed because i dare want to be spoken to normally.

I may have me and the family member that's worried about my weight sit down and talk about why they didn't bother to tell me the issue directly instead of passively implying that, because now i believe they believe I'm not at the same level as them, which means that they can't directly tell me if there is a problem in doing. It feels rather dehumanizing that they can't sit me down and tell me to watch my weight and intake because they care about me. 

Do they really care about me if they can't normally tell me that they are worried for my health, or they simply can't tell me without being aggressive...