Why not eat below BMR?

Ploogy

I've wandered through these forums and I see the idea of not eating below one's BMR touted as gospel. The usual line is that BMR is the minimum caloric needs of a body in order to function (the "if you were in a coma" line is often used). However, there is never any accompanying explanation as to why this number has any correlation to one's entrance into the dreaded starvation mode. The very reason we carry fat on our bodies is as fuel reserves for when we are not providing our body with adequate energy. If so, can someone point me to any scientific evidence that someone's body, if eating below BMR, will decide to catabolize its own organs instead of using fat reserves? It's actually quite counterintuitive in my eyes, and I'd love to learn what is behind this mechanism, if it exists.

As a corollary, for those who believe in the BMR as a baseline, there seems to be a conflict between those who believe that you simply need to eat enough calories to meet your BMR (regardless of any activity expenditure) versus those who say that one needs to at the least NET calories equivalent to BMR. Why does this conflict exist, if in fact, it is apparently unclear that BMR should even be seen as some sort of threshold?

Thanks in advance for the help on this! I could use it!

CristinaL1983

Bump because I'm waiting with bated breath to see the responses.

naseak

bump

missmegan831

bump

akp4Him

bump

Mads1997

Most dieticians will have you eating under your BMR if you have a lot of fat to lose.

Doberdawn

I don't think it is that your body begins to "cannibalize" the organs. The problem is that there is a certain amount of fuel that your body needs just to function. When you don't supply it, but you still expect it to do its job, you put a strain on those organs and jeopardize your health and doing damage to the body. It takes energy even just to burn the fat you want to use, just like it takes energy to digest and use the food you eat. Conversion, consumption, digestion, and waste systems all require energy. Expecting to get energy from them while not providing energy to run them is like expecting a combine harvester to plow fields so you can eat without putting any gas in the tank. I'll see if I can find any links that are more authoritative and scientific than this... but that's my basic understanding.

twinketta

I do not think it is about organs but more about muscle?

But having said that not feeding your body as a whole organism will eventually deplete and drain ie skin, hair, nails will not do well if you do not feed your body in a good way.

You will find lots of scientific evidence that anorexics can deplete their organs by eating below the BMR consistently.

This is the short answer, you sound educated, so you would not need me to tell you any of this?

Doberdawn

Twinketta is right about losing your Lean Body Mass too. You will lose muscle, a lot more than you want to. That is another problem with radical cutting diets.

Ploogy

This is the short answer, you sound educated, so you would not need me to tell you any of this?

No, it has nothing to do with education! If I was actually educated in this arena, I wouldn't be asking the questions, so rest assured that I am most definitely not. My reasons for asking is that I am trying to take a good, hard look at the principles espoused in this Community, and I feel that some of the fundamental precepts, like this, are just stated as accepted fact with no inquiry into where this comes from.

I don't think it is that your body begins to "cannibalize" the organs. The problem is that there is a certain amount of fuel that your body needs just to function. When you don't supply it, but you still expect it to do its job, you put a strain on those organs and jeopardize your health and doing damage to the body. It takes energy even just to burn the fat you want to use, just like it takes energy to digest and use the food you eat. Conversion, consumption, digestion, and waste systems all require energy. Expecting to get energy from them while not providing energy to run them is like expecting a combine harvester to plow fields so you can eat without putting any gas in the tank. I'll see if I can find any links that are more authoritative and scientific than this... but that's my basic understanding.

Cannibalize may be the wrong words, but the point is that BMR is spoken of as a threshold under which the body is detrimented, and starvation mode begins (some implying it is just around the corner, even). You are right that the body needs a minimum amount of energy, it must. However, even taking into account both the energy to mobilize fat and the rate at which the body is able to do this - which is what you I think are getting it - there isn't, on the face of it to me, any basis to see BMR as anything other than a useful number from which to calculate one's total daily energy expenditure. I don't see how from where a conclusion is drawn that it serves as some sort of threshold above which the body will grab from organs or feel the need to downregulate and enter "starvation" mode.

Ploogy

Absolutely, not questioning that. If someone's BMR was 2000 and they were 350lbs overweight, and instead of eating 4500 calories a day, they suddenly dropped to 2100, that would be, by all accounts, a drastic diet. But it's still above BMR! So technically no problems should exist. Just pointing out how I don't understand the magic of the BMR figure as a threshold for starvation and metabolic downregulation.

Twinketta is right about losing your Lean Body Mass too. You will lose muscle, a lot more than you want to. That is another problem with radical cutting diets.

gpizzy

My understanding is that your body goes for muscle before fat, and will eventually get used to operating at a reduced efficiency because there isn't enough new food energy. I dont have any links for you, just what I've read over the years from here, books, and websites.

I think it's a choice, do you want to lose fat or muscle? I personally want to lose fat, so I dont want to eat less than 1200 calories or go into starvation mode.

If you look at people anorexic who eat very little or nothing, they lose weight... lots, they lose all their muscle first and then can be 'skinny fat'. eek!

Doberdawn

There are some articles on Bodyrecomposition.com - excellent and informative site - that talk about these things. Apparently there was a study where folks ate below BMR to lose weight. But, then it damaged their BMR and their body reduced its functioning to correspond to the starvation conditions. When they wanted to return to normal eating for their sizes and to restore their BMRs to normal, there was no permanent damage to their metabolisms, but they had to regain all the fat they lost. So, how was that a good plan? "Even in the seminal Minnesota study, metabolic rate eventually rebounded to normal; of course the subjects had regained all of the fat they had lost as well for that to occur." It should be noted that some extremely obese folks tried doing this and damaged their metabolisms to where they couldn't lose excessive fat on very low calories because they developed insulin resistance. "One of my clients weighs 360 lbs and her BMR according to the the InBody is 2700 calories. The girl eats maybe 1200 calories a day and maintains that weight. Reversing insulin resistance by eating the proper foods and incorporating resistance training obviously helps. I am wondering if there is an approach to increasing calories systematically when working to reverse insulin resistance without gaining weight?" If you want more info on that, I suggest you contact Lyle, who runs that site.

Zangpakto

Truthfully... no reason. Doctors even prescribe VLC diets. which is under BMR.

Even a reported case of someone with a few vitamins and minerals solely living on fat for a year or something because he had so much to lose... And you know what? Maintained LBM....

It's myths that MFP decides upon and mods here enforce. They are not part of the medical science community, never will be and yet they pretend it.

Mads1997

Twinketta is right about losing your Lean Body Mass too. You will lose muscle, a lot more than you want to. That is another problem with radical cutting diets.

You will lose lean muscle mass if you do extreme cardio and eat over your BMR too.

peachfigs

you could die

OddChoices

It is easy to breakdown muscle than breakdown fat. As someone mentioned it takes energy to metabolize fat and make it available to the body. Hence if you eat below BMR, your body will first "cannibalize" the easier fuel source before turning to the fat stores.

ThickMcRunFast

Oh, this thread.

babydiego87

you could die

cmon, i heard you'd lose a limb at most.

twinketta

Twinketta is right about losing your Lean Body Mass too. You will lose muscle, a lot more than you want to. That is another problem with radical cutting diets.

You will lose lean muscle mass if you do extreme cardio and eat over your BMR too.

hmm!! elaborate on that one???

kimleroy

I'd just like to point out that while yes, it does take a very slight energy input to break down fat stores to be used as energy, you get a very large amount of energy out from it. So, biochemically speaking, you don't really need to have much available energy to break down fat because once you break down the first molecule, you get out enough energy to break down about 10 more.

lizzardsm

Have you thoroughly read this?

http://www.myfitnesspal.com/topics/show/654536-in-place-of-a-road-map-2-0-revised-7-2-12

From my understanding, muscle is more calorically dense than fat. So when eating below BMR your body is going to reach for the easiest source of calories to keep you and your organs functioning - and it will deplete both lean body mass and fat. Eating above BMR combined with strength training gives you the best bet for maintaining your BMR while in a calorie deficit (you cannot really add muscle mass when in a deficit, only strength gains). In essence, eating below BMR eventually slows your metabolism - and causes your weight loss to stall.

KenosFeoh

I do know why the body will burn muscle before fat. The fat reserves are a last resort against starving. The body will burn muscle first because muscle is metabolically active. The more muscle you have, the faster you will burn through that precious fat to stay alive. So the body reduces muscle mass first.

It's really a delicate balance that we have to find in order to burn fat while retaining muscle. Not eating less than your body requires to stay alive (BMR) is part of that balance.

paperpudding

am not sure of exact science and number crunching - and I dont follow the BMR/TDEE method many on here do - I just eat how many calories the thing tells me to eat for my age gender ,activity level etc plus any 'exercise earned' caloires - number happens to be 1540 plus excercise calories - but it makes sense to me to have a point where eating below this would be detrimental to your health - I like the way MFP recomends slow and steady weight loss, not drastic methods of extremely low caloric intake

I mean, obesity is not good but neither are eating disorders.

Hmmm, not sure if that answer was on topic or not.....

Lupercalia

I'm not into the whole "starvation mode" myth. The reason I don't eat below my BMR is that it causes your metabolism to slow over time. I don't think any of us on this site want that.

I also feel like crap when I don't eat enough calories...get very "hangry" and feel tired and blue.

2EggsSeparated

you could die

cmon, i heard you'd lose a limb at most.

How much do limbs weigh?

AnnInTexas

I actually started "medically supervised" weight loss last week with a doctor.
As part of my pre-planning my program, she set me up to have a RMR test -- that's where they determine your resting metabolism rate -- or the energy burned by your body just sitting down quietly. I'll be happy to share the findings:

My weight: 238 pounds
My height: 5'4"
My RMR: 1800 calories.... that's what my body needs to function.
An additional 540 calories was added to the total as "lifestyle & activity" -- getting up to go the copy machine, climbing stairs to the 2nd floor, etc. That's a total RMR of 2340 calories.

The determination is:
1800-2300 calorie daily intake will maintain my current weight.
1440-1800 calorie daily intake is the "weight loss zone."
Anything under 1440 daily calorie intake should be medically supervised.

I'm going back this Saturday to the gym, to have a VO2 test -- that's where they determine your optimal heart rate for weight loss. Most people tend to exercise in the cardio zone -- which is certainly great. But for someone like me who still needs to focus on weight loss - I need to work out at a different heart rate.

I think the key is "medically supervised." I also underwent a complete blood workup and EKG... which will all be repeated in a couple of weeks. As part of my plan I meet with a nutritionist every week and either the doctor or the PA. I am NOT doing the VLC diet, frankly because that kind of scares me... but knowing this other information is pretty helpful in helping me with my day.

AngryDiet

It's some sort of weird irrational claim that has really gained a lot of traction here. I've never seen anything that backs it up, other than some strange irrational beliefs about comas and "starvation mode."

There are certainly issues like losing LBM which should be considered. But that is a conversation about caloric deficit and LBM. Not about BMR. BMR is irrelevant and just muddles the conversation.

It seems to me that TDEE is a far more valuable number than BMR. With your TDEE you can predict weight loss, and you can predict LBM loss as well. With TDEE you can get a sense of what is right for you and what is inappropriate.

While TDEE can be derived from BMR, TDEE can be directly measured by anyone, while BMR cannot. All you need to do is track your weight and log religiously for a few months, and you'll get a pretty good idea of your TDEE. You don't need to use "best fit" formulas and you don't need to guess which cookie cutter activity level you actually are. (Odds are you are between two anyway).

I've been eating slightly below BMR for over a year now. I've been losing between 1 and 2 lb a week for most of that. Oddly I'm still alive. YMMV.

twinketta

This is the short answer, you sound educated, so you would not need me to tell you any of this?

No, it has nothing to do with education! If I was actually educated in this arena, I wouldn't be asking the questions, so rest assured that I am most definitely not. My reasons for asking is that I am trying to take a good, hard look at the principles espoused in this Community, and I feel that some of the fundamental precepts, like this, are just stated as accepted fact with no inquiry into where this comes from.

I don't think it is that your body begins to "cannibalize" the organs. The problem is that there is a certain amount of fuel that your body needs just to function. When you don't supply it, but you still expect it to do its job, you put a strain on those organs and jeopardize your health and doing damage to the body. It takes energy even just to burn the fat you want to use, just like it takes energy to digest and use the food you eat. Conversion, consumption, digestion, and waste systems all require energy. Expecting to get energy from them while not providing energy to run them is like expecting a combine harvester to plow fields so you can eat without putting any gas in the tank. I'll see if I can find any links that are more authoritative and scientific than this... but that's my basic understanding.

Cannibalize may be the wrong words, but the point is that BMR is spoken of as a threshold under which the body is detrimented, and starvation mode begins (some implying it is just around the corner, even). You are right that the body needs a minimum amount of energy, it must. However, even taking into account both the energy to mobilize fat and the rate at which the body is able to do this - which is what you I think are getting it - there isn't, on the face of it to me, any basis to see BMR as anything other than a useful number from which to calculate one's total daily energy expenditure. I don't see how from where a conclusion is drawn that it serves as some sort of threshold above which the body will grab from organs or feel the need to downregulate and enter "starvation" mode.

It really seems that you are very educated...and I am sorry to emphasise this point.

You will know this anyway, BMR has been calculated for a reason as our basic metabolic rate, this has been calculated scientifically, whether it is up to date I do not know?

Starvation mode is a little more hard to define, I am not aware of any hard facts in this century that it does exist?

But as I said in a previous post, if you eat below your BMR then you are depriving your `organism` generally of nutrients that it needs to `survive` in a healthy fashion.

ninerbuff

IF you had lots and lots of weight to lose, or say you're a person who doesn't exercise and has a sedentary life, then in those cases eating under one's BMR may not be a big deal.

IE. Person's BMR is 1500. Sedentary life brings TDEE to 1900. Person wants to lose a pound a week, so takes in 1400 a day.

A.C.E. Certified Personal/Group FitnessTrainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition

FromHereOnOut

Interesting topic.

I have been experimenting on myself and am (finally) seeing some results after increasing calories in. In my experimenting, my calories have been all over the place and I'm trying to come to a number that I can put as a baseline, which is why I'm interested in your thread. I'm wondering about netting below BMR, because this month I'm working out much harder than the past 2 months. I have a feeling I'll be netting below BMR because it might be too much to try to eat. However, I won't be EATING below BMR. To the contrary, I'll be eating quite alot and will give my body plenty of fuel and NUTRIENTS and the rest of what the body needs for my extra work outs can come from fuel storage (fat). I think this will work well.

As for the reasoning for not eating below BMR...I DO think it's about wrecking your metabolism. Your body is a magnificently adaptable organism. If you cut cals way down, your body will create energy-sparing and will remain there even after your cals increase to a more sustainable eating style. The new energy-sparing mode of your body will then have to store the "extra" calories that you introduce. In other words, the low cal diet will work upto a point, where you'll either plateau/stall, or you go into maintenance calorie level and you'll put on weight again. The other factor is stress to the body and the hormone changes that it creates. Stressing the body increases cortisol, which messes with metabolism and energy usage v. storage. This is all just my understanding of it. I don't have any studies, and in fact what I have read seems to suggest that scientist in this field don't entirely understand it, for example whether the increased calories (above VLC) flips some metabolic switch...or simply causes the body to create more movement (toe tapping, body swaying, etc) that adds up to higher expenditure. You could probably keyword search PubMed and find some things, but I've found that I had to just bite the bullet and experiment. I was terrified at first, but it worked out. My husband is a K.I.S.S. kinda guy and his take on my journey is this: eat the way you were eating (I wasn't eating alot of junk), but workout (I also wasn't working out). After experimenting, that's basically where I came back around to. I'm eating the way I was before, but working out (and working out more and more).