An easier way to setup goal calories - eating for who you wi

If you provide less than BMR in net calories, your body can NOT get this from itself, it will slow it down to require less.

This is completely not true. All dieting will cause your metabolism to slow down eventually. There is no magic number of calories you can stay under and not see this effect. The longer you diet and the greater your calorie deficit, the bigger the slow down but everyone experiences a slow down especially once they lose around 10-20 pounds and have been dieting for more than a few weeks.

Which part not true, that your BMR will not slow down, or you can't get that energy for BMR from the body itself, or if you provide less than the BMR? I'm thinking the last by your comments.

At the start of dieting your metabolism will slow down a tad, as you comment the amount depends on the level of constant deficit, it takes a bit to respond, so for awhile your BMR is high, you are eating lower than maintenance calorie and BMR by a little or lot. What comes next sets the stage for how it's going to keep going.
As you verify, the BMR does lower, because it cannot get the energy needs from itself. Part of the BMR is actually feeding the muscle and fat, and moving water around through all the cells.

There is a magic number you can stay under to not cause the BMR to lower permanently. Allowing it to pop back up to where it was once it recovers from constant shock. The amount you undercut it, as you state, determines the amount of drop. Not seen any study that nailed how long it takes. That seems to be genetic, or perhaps depending on how screwed up your metabolism is already, the observed yo-yo dieting syndrome.

What is the magic number - Your normal daily non-exercise activity calories.

Those type of activities that are mainly fat burning. If you don't feed that activity, it was already pulling from fat energy probably 60% of the calories needed. At that slow level, 39% glucose, rest muscle.
You next meal just slightly over BMR will easily top off the glucose stores for the next stretch, provide some protein for repair, and some fat for immediate energy use along with excess carbs/protein.
So not feeding that activity is not that bad.

Sadly most people only have 300-500 of that type of activity.

But not feeding your BMR is bad. So if it drops 200 calories worth of daily burning. Is that good or bad when your non-exercise daily activity only had 300-500? About 50%.
And lets say you exercise on avg 500 calories a day. That 200 is almost half of your exercise, free burning all day long, every day.

Now lets really throw a monkey wrench in and not feed that exercise. If diet alone dropped you 200 below, and now exercise unfed drops you another 500, the BMR is now making out with 700 less calories than what it could be burning. And if you keep that routine up long enough, you will lose some at first for a while, but how long until the BMR drops again for what you are constantly feeding it?

700 calories a day lost compared to what it was burning at a healthy level. 4900 calories a week not being burned. 1.4 lbs a week.
And since your exercise is just taking away from your body the calories for life, you aren't really burning that weight off after the BMR lowers.

So you can keep jack-knifing that routine. Lower, lose, lower, lose, lower, lose, stall, motivation failed, eat a tad normal, big gain, aggravation, disappointment, failure, try again.

Ugh.

Sorry about the spiel in return to your post, it was definitely not about your post. Just read a bunch of other topics where all these misconstrued ideas just don't cause some to wake up. One poster said she was now eating 1000 daily and burned 200-300 and no eat-back, and had stopped losing about 3 weeks ago. Several follow up posters said you need to exercise more or cut a tad more out.

Why not accomplish the same thing with as healthy a BMR as possible for as long as possible.