why do indians consider being on slim side is unhealthy?

I have always had fast metabolism , i eat a lot like more than my brother who is bulking , yet i dont really gain much fat , i am not malnutritioned tho , my bones are heavy i dont have excess fat on my body what irritates me to the core is "kuch khaati nhi hai kya" " mummy khana nhi deti kya " 😹😹🙏😹😹🙏typical lotpot komedy jokes like shut up man i dont wanna body shame but most of them are obese why would you shame me and not concentrate on yourself , the only one who defends me is my mum who retaliates by saying " achi baat h healthy hai " "haan iska saara khana m khaa jaati hu " or my aunt who wishes she had my figure 🥹 plus recently my cousin who passed neet got in medical started saying you are looking so pale iron kha yeh kr vo kr i have had my iron tested twice and the reports came perfectly fine ,if i was unhealthy i wouldnt be functioning properly , my reports are fine , my hair are healthy , skin is pretty much clean , i dont feel tired , i go for walks but gosh i feel like crying after hearing this bs again and again , there have been a phase where i started this unhealthy habit of binge eating just so i could gain weight and ppl would shut their mouth but that made me nauseous and kinda deteriorated my mental health , i dont do it anymore and to avoid this i rarely go to my relatives house , the thing is when i am abroad mostly people compliment me even my friends here few of them but i just cant seem to get it out of mind that i dont need to gain weight its all fine .