What's the reasoning behind eating AT LEAST your BMR?

Wow. You really have to ask?

BMR is absolute minimum. No moving. Just laying in bed.

When you get up, go to work, walk to the pub, have a beer and a sandwich, then go to the gym and lift heavy weights for an hour, all that is on top of BMR. That's your TDEE, which you seem to know o by are you asking. So, most people gain weight because they eat way above their TDEE. If you eat at TDEE. You will neither gain nor lose. If you eat less than TDEE, you lose. But, because your basic survival needs are at BMR, You don't want to eat below BMR. Somewhere above BMR and below TDEE is your weight loss program.

I hope that's clear.

It is clear; however, it doesn't answer my question as it completely disregards my argument.

Ok -- how about the following since you understand that below TDEE already creates a deficit.

Eating below your BMR is ok under certain conditions -- limited amount of time and for someone who has nutrient/calorie stores.

The issue isn't that you have to eat above a certain magical number. It is that at eating well-below a reasonable deficit you are going to have the following things going on:

1) insufficient nutrients - the less you eat, the less likelyhood you will have sufficient diversity and volume of essential nutrients. oops.

2) protein catabolic/anabolic balance - at large deficits the on going processes will tend to shift to a balance which favors using up protein from your muscles elsewhere. One particular place is nutrient transport - do you prefer to have muscles or have them go to make albumin miscelles to tranport food (that you aren't eating). Everyone that loses weight fights with this balance. Large deficits make it harder, much harder. About 1-3% of your protein is being replaced every day. One wants to assure that their is sufficient nutrients to keep that equilibrium in the right direction. Otherwise oops.

3) energy levels - if you are active, lower energy will impact performance in activities and general life. oops.

4) metabolic processes governed by hormonal balance - these process manage things your metabolism but also like hair, hunger, mood, skin and brain function. Long term you really do not want to screw up with that. big oops.

4b) fast drops impact your body in other ways: loose skin, internal elasticity and kidney stones are some of the other macro physiological risks.

5) mental - large deficits are mentally hard and lead to some disfunction (some of it driven by point 4) - this includes simply dropping the lifestyle change (too hard), binging, depression, moodiness to full eating disorders (see startvation studies). Another big oops.

6) lifestyle - one should be developing long term habits that work for a lifetime, and in all situations - below BMR eating is boring, painful and socially difficult.

I've been averaging nearly 1000 calories burned a day and lemme tell ya its hard to eat that back without cheating.

It is *never* "cheating" to maintain a reasonable calorie deficit. WTH?

I mean cheating on nutrition. It'd be hard to eat a 1000 calories of salad haha 1000 calories is a lot of extra food to make up. Its hardto make that 1000 calories back and not load up on unhealthy foods to do it. Especially when you're not hungry.

My BMR is 2100 and my TDEE is over 3200 i was eating around 1200 calories a day when I did it 2 years ago and lost a lot of muscle mass. My goal weight's BMR is 1800 (165lbs, 69"). I would suggest if you have to eat below your current bmr eat at your goal weight's BMR

Guys aand gals, if you eat below your TDEE and you lose weight you are in a fat burning caloric defecit. Why go above and beyond to eat below your BMR? muscle burn is a real possibility so why bother risking it if you can accomplish the same task eating above it? As stated previously why would you want to hinder skin elasticity to lose weight faster(debatable) especially if you want to look good. We aare trying to lose inches not lbs. Anyway hope you are all successful however you do it! Peace out!