hi Looulrs... aside from our ages, i'm in my 60's and retired, you are almost exactly in the same spot i was about 8 months ago. converting your kg/cm stats to lb/in, i take it you are 6' 3" and weigh about 260 lbs... a BMI of 32.5. before i started changing things around, at 184 cm, my BMI was close to 32. not that i had/ have a lot of reinforcement either, i live alone, at least i do not have any negative reinforcement. even worse for you, i can control what food is in the house. i have no temptations, because there are none around me. ok, i do have a big tub of sugar in the pantry, but i know that is exclusively for the hummingbirds and Christmas cookies i make by tradition. seriously not looking forward to that next month, but i'll have to see just how much i've learned this past year.
let me give you the good news first. i had made 3-4 attempts to get myself at least down to 200lbs. the memory of a joke that i feel today was sort of cruel, when i was on a softball team in my 20's, one of our teammates got the nickname of "point one ton"... 200 lbs if you do the math. he wasn't really that fat, but compared to the rest of us at the time (i would probably laugh at our fitness levels if i saw that same team today) he was what i'd refer to as pudgy. anyway, adapting some of the only ways i knew of losing, i found myself stalling out at about 210 lbs and could not seem to break through that boundary. i bounced back and forth between 210 and 220 for a few months.
then i started looking to the internet... not for weight loss programs, but listening to people a lot smarter about nutrition and how the body actually functions. these guys do not "sell" any programs in their talks, but i would recommend looking for lectures by Robert H. Lustig (on sugar consumption) and those of Jason Fung (on fasting). personally this was a revolution for me. after cutting sugar out almost completely and choosing a type of intermittent fasting that works for me, today i'm looking at a BMI of 25 and on a good track to hit the healthy 24 BMI or less by Christmas.
giving up sugar may be a lot harder for you than it was for me as i was never big on sweets or desserts, so this will take a lot of determination on your part. one motivation for you i can think of... imagine yourself maybe just shooting for a 210 lb goal (at your height, pretty similar to the level of my 200 lb goal for a start). unless you come from a truly heartless family, those people are going to see and comment on your change. YOU can be the example your other family members might need to get them to see what they are doing to their health.
i wish you the best of luck.
cheers...gary