How low can BMR become after a large loss?

[kindaoldguy]

This is a bit of a science question; I welcome all opinions!

I'm a ~45yo male, 6'3". BMR estimates for me always hover around 2000-2200 cal/day. Ever since a large weight loss several years ago, I'm convinced it's more like 1500 and it refuses to go up. People from shows like The Biggest Loser have said the same thing -- that their BMR is way down after a weight loss and stubbornly refuses to go back up.

So my question is: What does the resting adult male body genuinely need per day if it certainly isn't 2,000 calories, and might not even be 1500? Can it go as low as 1000? or lower?

I realize many of us might be counting calories wrong, but there are too many people complaining about BMR drops for everyone to be counting incorrectly.

Feel free to share your opinions..thanks!

-j

[AlexSays]

This is a bit of a science question; I welcome all opinions!

I'm a ~45yo male, 6'3". BMR estimates for me always hover around 2000-2200 cal/day. Ever since a large weight loss several years ago, I'm convinced it's more like 1500 and it refuses to go up. People from shows like The Biggest Loser have said the same thing -- that their BMR is way down after a weight loss and stubbornly refuses to go back up.

So my question is: What does the resting adult male body genuinely need per day if it certainly isn't 2,000 calories, and might not even be 1500? Can it go as low as 1000? or lower?

I realize many of us might be counting calories wrong, but there are too many people complaining about BMR drops for everyone to be counting incorrectly.

Feel free to share your opinions..thanks!

-j

No, fat mass only accounts for a relatively small part of your BMR, lose all the fat you want but you will still have the same amount of bones, organs, blood, digestive processes, liver processes, neural processes, active transport within cells etc etc etc.

It is unlikely to fall below maybe 18-1900 in someone of your height, and that would be if you are damn lean and have little muscle mass. How do you 'know' your BMR is 1500? There is no real way to accurately measure it...

Of course your BMR will drop after a large loss but not by as much as you think. It is likely that your BMR was actually higher than you think before your weight loss and is now just at a normal level


EDIT: additionally, morbidly obese people often perceive a 'huge' drop in BMR because usually all they have to do is cut out snacks and they will lose at a relatively high calorie intake (say 2700-3000 cals). Once they are having to move and support a significantly smaller body-weight they often complain that their metabolism has 'crashed' when in reality once they are back inside more regular overweight ranges they have to eat a lot lower like everyone else

EDIT EDIT: As the reasoning for my first comment around fat and BMR: Fat is not a metabolic tissue (unlike muscle mass), which means it does not actively require many calories to maintain, the calories it 'burns' it usually burns indirectly through the high NEAT it takes to live with greater fat mass.

EDIT EDIT EDIT: On the biggest loser they lose fat at a fully idiotic rate, likely losing a lot of lean mass in the process despite the pointlessly intense training they do. Losing a lot of your lean mass will result in a lowered BMR

[blue9steel]

At 6'3" 211lbs, 1500 sounds way off. I have a slow metabolism and I'm smaller than you at 5'10" 198lbs but my BMR is around 1950 or so. It did drop a fair amount when I lost my first 60lbs but it was right in line with what the online calculators suggested for someone that weighs less.

Most likely answer is that you're not counting accurately or forgetting to count something. That's happened to me multiple times. At one point I was undercounting homemade pizza calories by 35%, in another instance I was leaving out 300 calories a day worth of coffee creamer.