What's with the "don't ever go below BMR" stuff?

jonnythan

Don't people have rest days? TDEE - 20% or TDEE - 500 can often go a bit below BMR, but common wisdom on MFP seems to be that on any day you go below BMR your metabolism will crash and your hormones will be wrecked.

Where's the reasoning behind this? BMR isn't a magical number - it's just what your TDEE would be if you didn't get out of bed. Your body doesn't have "BMR calories" and "TDEE calories." They're just calories.

If you want to lose weight, eat TDEE - 20% or TDEE - 500 calories. If that drops below your BMR occasionally, don't worry about it. That's fine. There's nothing special about BMR. It's just the starting point for calculating TDEE.

I wonder what these "never below BMR ever!" people have to say about intermittent fasting plans which have you eating well below BMR, or fasting completely, every now and then. Perhaps they think these plans will wreck your hormones.

jonnythan

I am off to the gym. It's deadlift day! I can't wait to see what's been posted by the time I get back.

auddii

I always assumed that it was don't eat below you BMR for long periods of time because it can lead to adaptive thermogenesis.

tisha_rae

Don't people have rest days? TDEE - 20% or TDEE - 500 can often go a bit below BMR, but common wisdom on MFP seems to be that on any day you go below BMR your metabolism will crash and your hormones will be wrecked.

Where's the reasoning behind this? BMR isn't a magical number - it's just what your TDEE would be if you didn't get out of bed. Your body doesn't have "BMR calories" and "TDEE calories." They're just calories.

If you want to lose weight, eat TDEE - 20% or TDEE - 500 calories. If that drops below your BMR occasionally, don't worry about it. That's fine. There's nothing special about BMR. It's just the starting point for calculating TDEE.

I wonder what these "never below BMR ever!" people have to say about intermittent fasting plans which have you eating well below BMR, or fasting completely, every now and then. Perhaps they think these plans will wreck your hormones.

I think I was the OP on that post today.

PERSONALLY - I don’t see a problem if you “occasionally eat under BMR” However, I posted what I did and chose the options that I did for myself because I realized that I was consistently eating under my BMR - I had poor eating habits before and believe that I had indeed slowed my metabolism.

I love food and if I can eat more and still lose weight that is the option I would choose, but I want to make sure that my body is also fueled with good nutrition.

I don’t think you will die eating under BMR.

To each their own, I suppose.

cwolfman13

You can be below your BMR from time to time...it's consistently being below your BMR that is bad. I have days that I my caloric intake is slightly below BMR and other days where I'm over and it nets out...over the course of a week, I'm always over my BMR.

Also, BMR...well not a magic number, but yes, it's a real number and it is a medical term, not something made up on MFP or something...it's the calories doctors would feed you through a tube if you were in a coma to maintain proper organ function...so being below your BMR routinely over a period of time does cause a host of issues. Your body does have BMR calories...the calories just to maintain basic functions...I don't know why you would think you don't have BMR calories. This is easily verifiable with a little research or just talking to a doctor. If you were in a coma and the doctors routinely fed you substantially less than your BMR, you would eventually die...very slowly, but eventually, you would die.

People who have tons of weight to lose can sustain being below their BMR for longer than someone with 10-20 Lbs to lose as well.

Yooperm35

I zig-zag my calories so I'm below or above. Keeps my body guessing

evileen99

As an occasional occurrence, it's no big deal.

It's when people have been doing it for weeks that it becomes an issue for your health. You know, those that eat 1000-1200 calories a day and don't eat back their exercise calories.

cmriverside

Every now and then is a lot different than "A Weight Loss Plan For Daily Life."

Under BMR works for a while, till it doesn't. If you're obese, it works for a teensy bit longer. Then it doesn't.

Jennystimetolose

I don't understand about TDEE, tried to work it out but I ain't got a clue so if anyone would like to do it for me I would be very grateful , I am 5'2, 217 pounds and 39 years old for the past 2 months I have been eating between 1100 and 1300 calories and I swim about 4 to 5 times a week, I did have a look at trying to work it out myself and it says my TDEE is 2638, what I want to know is am I having the right amount of calories

BarbieAS

OP, I tend to agree with you, at least in that I don't understand it.

So your body has a certain number of calories it burns every day just to stay alive. Awesome. And, yes, your body needs to get those calories from somewhere in order to function. I'm still with you. BUT, if you don't consume all of those calories in food, won't your body just take those calories from fat and muscle stores, the same way it takes all the other calories it needs if you're eating in a deficit? Like, it comes off as between TDEE and BMR, your body is ok burning fat/muscle to make up that difference, but once you hit BMR all heck breaks loose and your body can't do that anymore? I don't understand. Yes, you need to eat enough calories to give you the nutrition and energy you need to function every day. But there's nothing magic about BMR.

stumblinthrulife

I think half the confusion is BMR vs. RMR.

From what I can make out, the calculation that most people think is BMR is actually RMR - Resting Metabolic Rate. i.e. what you'd burn laying in bed all day. BMR is one step lower - as I understand it pretty much what you'd burn if you were in a coma, and what a doctor would feed you via IV. True BMR is measured fasted upon waking in a darkened room, so that even your digestive system is inactive.

Consistently eating below your true BMR is probably not a great idea, because you have your body dipping into reserves for everything including digestive functions - I don't know the science, but intuitively that seems like a bad idea.

Eating below your RMR once in a while is probably fine, though you may be dipping into reserves for certain bodily functions. I think it would be a pretty miserable existence though, and even if not unhealthy it would probably be unsustainable.

tobejune

Who cares about BMR... If you ask me, the one rule we should all be following is.... Don't eat 30 minutes before swimming because YOU WILL DIE (after your body goes into hibernation starvation hormonal imbalance mode - that is if your model comes with those options.)

sofielein

I think there are like 13.5 calories between my BMR and my RMR. I think I'll just quit.

MsPudding

Don't people have rest days? TDEE - 20% or TDEE - 500 can often go a bit below BMR, but common wisdom on MFP seems to be that on any day you go below BMR your metabolism will crash and your hormones will be wrecked.

That's odd - weren't you on an IF thread blasting 500 calories for 2 days a week as 'starving yourself'?

SRH7

I don't understand about TDEE, tried to work it out but I ain't got a clue so if anyone would like to do it for me I would be very grateful , I am 5'2, 217 pounds and 39 years old for the past 2 months I have been eating between 1100 and 1300 calories and I swim about 4 to 5 times a week, I did have a look at trying to work it out myself and it says my TDEE is 2638, what I want to know is am I having the right amount of calories

Eat to 20% less than your TDEE (which I've just calculated and got the same figure as you).

That means eat 2110 each day, whether or not you exercise (your exercise calories are calcuated into this figure).

And have a think about joining these groups (lots of supportive, friendly people):

http://www.myfitnesspal.com/groups/home/8017-in-place-of-a-road-map

http://www.myfitnesspal.com/groups/home/3817-eat-more-to-weigh-less

tootoop224

My understanding is that if you eat below your BMR, your body won't get enough nutrients. So, yes you will burn fat and muscle for energy, but it won't have all the nutrients it needs.

Jennystimetolose

I don't understand about TDEE, tried to work it out but I ain't got a clue so if anyone would like to do it for me I would be very grateful , I am 5'2, 217 pounds and 39 years old for the past 2 months I have been eating between 1100 and 1300 calories and I swim about 4 to 5 times a week, I did have a look at trying to work it out myself and it says my TDEE is 2638, what I want to know is am I having the right amount of calories

Eat to 20% less than your TDEE (which I've just calculated and got the same figure as you).

That means eat 2110 each day, whether or not you exercise (your exercise calories are calcuated into this figure).

And have a think about joining these groups (lots of supportive, friendly people):

http://www.myfitnesspal.com/groups/home/8017-in-place-of-a-road-map

http://www.myfitnesspal.com/groups/home/3817-eat-more-to-weigh-less

thankyou for that

jonnythan

My understanding is that if you eat below your BMR, your body won't get enough nutrients.

Which nutrients will it not have enough of?

jonnythan

Every now and then is a lot different than "A Weight Loss Plan For Daily Life."

Under BMR works for a while, till it doesn't. If you're obese, it works for a teensy bit longer. Then it doesn't.

Yes, but no one is saying do it for daily life. Or even as a weight loss plan.

I'm saying that it's occasionally OK to dip below BMR on days when TDEE isn't much over BMR. However, there are people saying that no one should go below BMR ever, not even once.

stumblinthrulife

Don't people have rest days? TDEE - 20% or TDEE - 500 can often go a bit below BMR, but common wisdom on MFP seems to be that on any day you go below BMR your metabolism will crash and your hormones will be wrecked.

That's odd - weren't you on an IF thread blasting 500 calories for 2 days a week as 'starving yourself'?

I think there's a pretty big difference between eating below 1800 calories (my rough BMR) and eating 500 calories. Certainly enough of a difference to justify different views of each.

SideSteel

Don't people have rest days? TDEE - 20% or TDEE - 500 can often go a bit below BMR, but common wisdom on MFP seems to be that on any day you go below BMR your metabolism will crash and your hormones will be wrecked.

Where's the reasoning behind this? BMR isn't a magical number - it's just what your TDEE would be if you didn't get out of bed. Your body doesn't have "BMR calories" and "TDEE calories." They're just calories.

If you want to lose weight, eat TDEE - 20% or TDEE - 500 calories. If that drops below your BMR occasionally, don't worry about it. That's fine. There's nothing special about BMR. It's just the starting point for calculating TDEE.

I wonder what these "never below BMR ever!" people have to say about intermittent fasting plans which have you eating well below BMR, or fasting completely, every now and then. Perhaps they think these plans will wreck your hormones.

I understand what you're getting at and I agree. This is especially true in people who are very sedentary overall (low NEAT).