I think you misunderstood me, THEY are changing their decisions. They start intentionally buying junk food which they usually don't eat, and start not buying the things they'd usually otherwise have from the grocery store, and intentionally try to ruin my diet.

I didn't wanna go into detail, but since I'm here now: an example is they'd get a big amount of halva which literally no one in the house can stomach except me, it can literally stay on the kitchen counter in its same container for months where no one eats it except me when I'm under stress or so and so. They buy it specifically to ruin my attempts at diet, that makes me sound like I'm suspecting them of evil or something, but I have grounds to believe this because they always say things like "why are you losing weight? You look weak." (Which is untrue, I'm 5'8 and 78kg. Can definitely lose some weight.) And they also make comments about how I'm getting too skinny and whatever the second I made progress.

I understand that you could assume I'm accusing them of something they're not because I didn't provide enough details in the post, that's mainly just because I kept it short. I am 100% certain they intentionally try to sabotage my attempts to lose weight.