BMR is variable.
It's why when we talk about deficits and surpluses we are actually doing hand-waving around something critical, on any given day, how do you even know what your BMR/RMR is?
Contestants that starved themselves on the biggest loser showed a 500kcal reduction in RMR 6 years later. If they'd just plugged themselves into a calculator and eaten the prescribed allotment daily, they'd be gaining the weight back quite rapidly. And that's exactly what happened to most of them as it turns out.
My whole point was that some amount of weight "a year" isn't how that would work. The only way you keep gaining weight every year is that if every year, you eat more and/or exercise less than you did the prior year. If you eat too much, but the same too much, every year, you'll be overweight, but you won't keep gaining weight every year forever.
> Contestants that starved themselves on the biggest loser showed a 500kcal reduction in RMR 6 years later.
That makes sense, since they lost a bunch of weight and RMR is tied to weight.
The lower RMR remained and sometimes continued to drop after they regained the weight.
Any normal person cannot assume that their RMR is something they get off of a website calculator, or that it will behave like linearly. Speaking as someone formerly fat, the metabolic adaptation did persist for years after I lost all the weight, putting me around 400 below where I should have been on the chart. It is still quite annoying, though it has lessened.
No it doesn't. One of the factors that determines your BMR is your weight, so adding any constant amount of calories every day only affects your weight by a constant amount. Eating an extra 10kcal every day might give you 2lbs, total, ever in your life.