Eating Below your BMR... Why is it bad?

treetop57

Studies don't show either that fat loss stops when you do [eat below your BMR], just that it slows.

Which studies?

I linked them already in this thread in fact. Mostly on the link with anorexia and other eating disorders, where it affects production of cortisol and other metabolic regulators. Give it a read

This? http://scholar.google.ca/scholar?hl=en&q=anorexia+metabolism&btnG=Search&as_sdt=0,5&as_ylo=&as_vis=0

It's just a google search for anorexia and metabolism. Which particular studies do you mean when you say: "Studies don't show either that fat loss stops when you do [eat below your BMR], just that it slows."

Chagama

so, help me make sense of this. In order to lose weight you HAVE TO have a calorie deficit. So whether you're eating at, above, or below your BMR, the only way you can lose weight is if at the end of the day/week, etc you are burning more calories than you're consuming.

So why would eating below your BMR mean that your calorie deficit is made up by your body from muscle, but at or above your BMR it's from fat?

Either way, it's a deficit and your body needs to make up that deficit by using some of your body tissue.

This what always confuses me on this topic. It can't be true that eating below your BMR means your body will use up muscle, but above that it will be from fat. That would mean your body needs to know ahead of time how much you are going to eat later on so it would know where to get energy from early on. Obviously that can't happen.

It also seems to me that your body can't differentiate which calories are being taken in to support basic functionality of the body and which ones are for extra activity above that. Calories in are calories in, and calories out are calories out.

Now, clearly if you are eating too little, nutrition becomes a big problem, it's tough to get all the nutrients you need and that's a problem. But, if you take care of that (which the concentration camp victims couldn't do), your body shouldn't care whether a 200 calorie deficit is above or below your BMR.

And the claim that a pound of muscle burns up to 80 calories more than a pound of fat during a day is not accurate. I can't find my source, sorry, but I believe it is more like 4 calories per day. If it were 80, Someone who converted 30 pounds of fat to muscle while losing a large amount of weight would see their BMR go up by 2400 calories. That also doesn't seem possible to me.

Or,. another way to look at it, a 200 lb male with 30% muscle (reasonable numbers not requiring any great physical fitness level) would have 60 lbs of muscle which means those 60 lbs of muscle would require 4800 calories more than if they were fat. That's just for the muscle. Add in calories for the rest of your body's organs and stuff and you would have a BMR of up over 6000 calories per day.

Maybe I'm being too simplistic, and maybe I'm missing something (I don't have a medical background), but that's how it seems to me.

kenny_johnson

Another thought; there are a few people who have posted that they had their BMR tested professionally. One was something like new leaf testing. In any case, their BMR's were a lot lower than some I have seen by just putting your measurements into a website. One girl who was very close to goal had a BMR tested at 1,100! I am thinking that everyone is different and just like eating 1,200 calories doesn't not work for everyone, using a formula off of a website does not work for everyone either.

That's the other problem (and someone mentioned it). There is a probably a fairly large margin of error for all this. How accurate is your estimated BMR? How accurate is your calorie intake estimate? How accurate is your exercise expenditure estimate? Etc.

treetop57

And the claim that a pound of muscle burns up to 80 calories more than a pound of fat during a day is not accurate. I can't find my source, sorry, but I believe it is more like 4 calories per day. If it were 80, Someone who converted 30 pounds of fat to muscle while losing a large amount of weight would see their BMR go up by 2400 calories. That also doesn't seem possible to me.

Or,. another way to look at it, a 200 lb male with 30% muscle (reasonable numbers not requiring any great physical fitness level) would have 60 lbs of muscle which means those 60 lbs of muscle would require 4800 calories more than if they were fat. That's just for the muscle. Add in calories for the rest of your body's organs and stuff and you would have a BMR of up over 6000 calories per day.

Maybe I'm being too simplistic, and maybe I'm missing something (I don't have a medical background), but that's how it seems to me.

I believe the number is more like 10 calories per pound per day. I base that on the Katch-McArdle Forumula for BMR, which uses a factor of ~22 calories per kilgram of lean body mass:

Other formulas exist which take into account lean body mass, two of which are the Katch-McArdle formula, and Cunningham formula. It should be noted, however, that the Cunningham formula is used to predict RMR instead of BMR.

The Katch-McArdle Formula (BMR):

P = 370 + 21.6 x LBM , where LBM is the lean body mass in kg.[5]

. . . .

The Cunningham Formula (RMR):

P = 500 + 22 x LBM , where LBM is the lean body mass in kg

Since lean body mass is metabolically active vs. fat cells which need very few calories to be sustained, these formula tend to be more accurate, especially with athletes who have above average lean mass and little body fat.

http://en.wikipedia.org/wiki/Basal_metabolic_rate

ladyraven68

I like the way Vaclav Gregor (Greg) put it....All credit goes to Greg.


Metabolic slow down & “Starvation mode”
According to diet programs, you should experience metabolic slow down or starvation mode, when you are not eating regularly or eating below your BMR (explanations differ sometimes, which I found very entertaining btw). There is no study that would support that, quite the contrary. But instead of some research that you will not understand I’ll give you the most simple and logic explanation. Just look at the pictures of people who survived the holocaust or some tragedy and have been left for months or years without food. Did they trick the metabolism and starvation mode? I don’t think so. That means that eating less or fasting will not put you into “starvation mode” and your metabolism will not slow down.

It’s really nothing to be concerned about. These things exist only to confuse you and trick you into buying more food and supplements. It’s just business, sad but true. There are tons of researches and none of them will ever speak about things like starvation mode and metabolic slow down. In this researches when people lost a lot of weight there metabolism slowed down about 100 calories. That’s one large coffee. And I would say that it didn’t slow down, it just came to the normal level from being overweight. Why? Because BMR (Basal Metabolic Rate) is calculated by your height and your lean body mass. So when you lose weight, your lean body mass number decreases.

I'm sorry... have you seen those pictures of people from the holocaust? They sure looked starved to me. No muscle, no fat, just skin and bones. What did their internal organs look like? Is that what you would like to look like?

What everyone is saying you CAN eat below... but it is NOT recommended for Health reasons. No one wants you to look like a Holocaust Survivor or end up in the hospital because your organs have shut down since they were not needed.

But the “Starvation mode” idea here is that you can not loose weight in starvation mode. You have to increase those calories above the BMR. to loose. That is not true. It may be unhealthy but if you have a lot of weight to loose it can be done.

Actually, nobody has said you can't lose weight eating under BMR, they mainly said that you will lose more muscle by eating under BMR then with a sensible defict from TDEE.

Deducting up to 20% from TDEE is a sensible defict, You will not go under BMR by deducting 20% from TDEE, as even sedentary TDEE are BMRx1.2.

The aggressive deficit is what causes losses over 1% or over the ideal 1-2lbs of weight, and results in more muscle along with fat being lost. The lost muscle is then what results in the reduced BMR and then makes it easier for people to gain weight the next time.

There is a maximum amount of fat that the body can lose at once, anything over that will be lean mass - Lyle Mcdonald had an article but I can't link from my phone, but will find it later if you haven't found it first.

therealangd

I don't think it matters until you are pretty lean already. If you look at all the "resources" that promote this, they are the body building sites where they promote a very low body fat % or written by body builders. For the majority of people it doesn't matter. Your body will use it's fat stores for energy.

sktllmdrhmz

Another thought; there are a few people who have posted that they had their BMR tested professionally. One was something like new leaf testing. In any case, their BMR's were a lot lower than some I have seen by just putting your measurements into a website. One girl who was very close to goal had a BMR tested at 1,100! I am thinking that everyone is different and just like eating 1,200 calories doesn't not work for everyone, using a formula off of a website does not work for everyone either.

I'm one of those people, and my measured BMR is 2540. Can anyone really tell me with a straight face that to lose weight I need to eat MORE than 2500 calories?

I think the body is a lot smarter than we give it credit for and it's not going to behave as stupidly as a "starvation mode" would indicate. I would assume that if you were to just cut calories, your body is going to take energy where it can get it because that's what it needs. Why shouldn't it take muscle if you're not doing anything any differently? But if you were to cut calories and do resistance training, then you're body is gonna know it needs the muscle and it will focus on taking energy from the fat. My unsubstantiated opinion is that your body is going to adjust the ratio of muscle to fat lost how it sees fit. If you need muscle and have the nutrients necessary to build more muscle, then why the hell would your body take muscle if there's fat available?

Now, if only I knew of some studies that backed my thoughts.

sktllmdrhmz

There is a maximum amount of fat that the body can lose at once, anything over that will be lean mass - Lyle Mcdonald had an article but I can't link from my phone, but will find it later if you haven't found it first.

That's the first piece of info I've seen that makes this make sense. I'd like to find that article.

Masterdo

Studies don't show either that fat loss stops when you do [eat below your BMR], just that it slows.

Which studies?

I linked them already in this thread in fact. Mostly on the link with anorexia and other eating disorders, where it affects production of cortisol and other metabolic regulators. Give it a read

This? http://scholar.google.ca/scholar?hl=en&q=anorexia+metabolism&btnG=Search&as_sdt=0,5&as_ylo=&as_vis=0

It's just a google search for anorexia and metabolism. Which particular studies do you mean when you say: "Studies don't show either that fat loss stops when you do [eat below your BMR], just that it slows."

Well, you are right. I meant that search indeed, since they do also eat below BMR, but that was probably a leap.

Here is a nicer one:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC333231/pdf/jcinvest00645-0194.pdf
In this one you can find a nice survey of similar studies made in the past and a comparison of results. You can also see in the charts the weight loss and the BMR variation during the study. They kept eating below BMR all along, and the diet was constant throughout the weight loss. The conclusions tells how much of that weight was from fat stores, and how it relates to other studies on the subject. This one clearly mentions though that it is short term, and they analyze how this may or may not reflect on longer terms.

The fact is that these findings are lower than what other studies achieve like this one, that analyses weight loss composition on men and women (not severely obese) : http://ukpmc.ac.uk/abstract/MED/7713045
You can see some difference in lean body mass loss using different methods, none of which as as extreme as those in the first study.

There
But still, metabolic damage shown in anorexia patients is still relevant I think, it's just an extreme.

EDIT : Oh, and note that in both cases they lose fat, lean mass and water. It's just the ratios that change

cwilhelm40

What is your BMR?

MoooveOverFluffy

My understanding is that your BMR stands for the number of calories you would burn in a 24 hour period if you did nothing but lay still. Obviously, none (most) of us aren't going to just lay in bed all day long, so we're going to burn more than calories than our BMR just by getting out of bed and getting dressed.

If you figure out what your TDEE is, that's your maintenance level. Cutting calories from your maintenance level will cause you to lose weight. For the record, i'm sure you can lose weight eating below your BMR too, but how will you feel? Will you have enough energy?? Is it sustainable?? Why go that low if you don't really have to?? That's my two cents.......

silverbullet07

There is a maximum amount of fat that the body can lose at once, anything over that will be lean mass - Lyle Mcdonald had an article but I can't link from my phone, but will find it later if you haven't found it first.

That's the first piece of info I've seen that makes this make sense. I'd like to find that article.

Agreed. I would like to see it too.

zwienerdc

AS a doctor in training I can add that eating below your BMR is not advised and here is why. Your body need a certain amount of calories to survive and maintain function. This amount of calories is referred to as your BMR or Basal Metabolic Rate. It is the number of calories that your body needs to maintain itself. This maintenance includes maintaining fat cells that are in your body as well as organs, and function. When we determine BMR this is basic and is the amount of basic need. When we think about cutting calories this is determined from our RMR or Resting Metabolic Rate. This is the amount of calories that we typically burn doing our daily activities. This is the number that we use to determine a calorie defect.

This is the reason that shows like biggest loser has people cut calories well below their BMR but not for an extended period of time and includes weight training and education.

Your goal for eating should be between these two (BMR and RMR). Your body likes to burn muscle rather than fat. This stems from the primal side of use that we would rather have warmth and resources (fat) than muscle. When you eat below your BMR, your body needs to get calories from somewhere. This usually happens with your body breaking down muscle that it determines that you do not use and using those calories as fuel.

You might have heard that each fat molecule has about 9 calories in it and each carb and protein has about 4. This means that the body is not being the most efficient and explains why it takes longer to shed fat than it does to gain it. The bottom line is that the body likes fat and wants to keep it. This is why any descent weight loss program that is to be maintained should include a descent amount of weight training to build muscle to help maintain their bodies BMR and keep the pounds off.

I know that this is a long winded response to a simple question but the bottom line:

Eating below your BMR is not advised and your goal should not to be losing weight for just this month or year but to change your lifestyle and be able to be healthier in the long run.

kenny_johnson

Here is a nicer one:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC333231/pdf/jcinvest00645-0194.pdf

A B S T R A C T: The effects of starvation, an 800-kcal mixed diet and an 800-kcal ketogenic (low carbohydrate-high fat) diet on the composition of weight lost were determined in each of six obese subjects during three 10-day periods.

That is a study of people on an 800 calorie diet, not just people eating below their BMR. The one thing I found interesting though is that it said, "The mean decrease in BMR (12.3%) almost exactly paralleled the mean decrease in body weight
(13.3%)." Not maybe, I'm not understanding that correctly, but it sounds like that is what we'd expect. As you lose weight, your BMR lowers because it doesn't need as much energy to sustain a lower weight.

The fact is that these findings are lower than what other studies achieve like this one, that analyses weight loss composition on men and women (not severely obese) : http://ukpmc.ac.uk/abstract/MED/7713045
You can see some difference in lean body mass loss using different methods, none of which as as extreme as those in the first study.

I couldn't see the full text, but the article seemed to be about the results of exercise on maintaining lean body mass while dieting.

But still, metabolic damage shown in anorexia patients is still relevant I think, it's just an extreme.

I don't think its relevant, because I think there is a big difference between someone eating an 800 calorie diet and someone eating a 2000 calorie diet (but still below their BMR).



EDIT : Oh, and note that in both cases they lose fat, lean mass and water. It's just the ratios that change
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ladyraven68

There's also an article in here regarding loss of lean mass on a high deficit - http://www.myfitnesspal.com/topics/show/424130-why-you-don-t-want-to-set-your-cal-deficit-too-high

This can be staved off with eating more protein, but lets face it, not that many of the people eating under BMR are getting 1g of protein per lb of lean mass.

kenny_johnson

AS a doctor in training I can add that eating below your BMR is not advised and here is why. Your body need a certain amount of calories to survive and maintain function. This amount of calories is referred to as your BMR or Basal Metabolic Rate. It is the number of calories that your body needs to maintain itself. This maintenance includes maintaining fat cells that are in your body as well as organs, and function. When we determine BMR this is basic and is the amount of basic need. When we think about cutting calories this is determined from our RMR or Resting Metabolic Rate. This is the amount of calories that we typically burn doing our daily activities. This is the number that we use to determine a calorie defect.

This is the reason that shows like biggest loser has people cut calories well below their BMR but not for an extended period of time and includes weight training and education.

Your goal for eating should be between these two (BMR and RMR). Your body likes to burn muscle rather than fat. This stems from the primal side of use that we would rather have warmth and resources (fat) than muscle. When you eat below your BMR, your body needs to get calories from somewhere. This usually happens with your body breaking down muscle that it determines that you do not use and using those calories as fuel.

You might have heard that each fat molecule has about 9 calories in it and each carb and protein has about 4. This means that the body is not being the most efficient and explains why it takes longer to shed fat than it does to gain it. The bottom line is that the body likes fat and wants to keep it. This is why any descent weight loss program that is to be maintained should include a descent amount of weight training to build muscle to help maintain their bodies BMR and keep the pounds off.

I know that this is a long winded response to a simple question but the bottom line:

Eating below your BMR is not advised and your goal should not to be losing weight for just this month or year but to change your lifestyle and be able to be healthier in the long run.

I've already responded to almost this exact post by about 15 other people. See posts above. In fact, my first post is a response to pretty much this exact argument. In order to lose weight, you need to have a calorie deficit. That means, you are burning more calories than you are consuming. Your body needs to make up this deficit by using your body tissue. Why would your body take it from muscle if you eat below BMR but from fat if you eat above BMR? I still haven't seen this adequately answered.

Vespyr

From a biochemical standpoint...your body does just say hey lets use up energy from muscle first then eat the fat. Nothing about our bodies is that cut and dry. You eat and your body utilizes the energy from that to power itself. Glucose is the source of energy for the body. Every single one of your cells has mitochondria...these are the powerplants of the cells they convert glucose to usable energy. Now glucose can come from a variety of sources...that package of jelly beans, the glycogen in your muscles and liver and your from fat cells. Your body is lazy. It uses the easiest source the most ie. sugar from the extra large latte you just drank. Then it goes for glycogen because it's really easy to convert that to glucose...then your fat. Keep in mind all of these processes are going on all of the time. You're not just using fat, food or muscle exclusively. If you're working out a lot and your food intake isn't enough to support your system (BMR) your body will up the breakdown of muscle and fat (not one or the other...both) But like I said before muscle is easier so it uses more. Fat is long term, slow burning fuel (like a tallow candle) which is why when your body thinks it's in for hard times (you're not eating enough to support its daily functions) it will try to retain fat and use up other expendible sources first...simply because it will last longer (more calories in it) so hopefully you'll find some food before you run out. Someone mentioned bears...they don't put on muscle in the winter because they would starve, fat is able to sustain them longer...I'd have to look it up but I'm pretty sure they lose a ton of muscle mass too...but they're bears nobody messes with them anyway. Plus humans don't hibernate...but yea. Heck cats can go into liver failure if they don't get enough calories within a very short period of time (like a week)...they suck at being hungry. Even super obese cats, if they lose weight too fast, can die. Glad I'm not a cat. Wouldn't mind being a BA bear though.

Real life example: My sister started lifting a year ago...she was intense about it and lost a lot of body fat (not that she had much to start with) she worked hard and got down to 13% BF. More recently she began eating cleaner and ingesting fewer calories as a result. She doesn't track calories btw. Within a short time (2 months maybe) her BF went up to %17 without her workouts changing. Her body is hungry and scared and it's preparing for the worst.

You can lose weight by eating below your bmr. You might be hungry or hangry and you might not last in the long run. You might see results like my sister did. Anorexia works...starvation works...is it sustainable or healthy...err no.

I think what a lot of people are trying to say is that you need to find a balance where your body is getting enough energy to fuel it properly, you're not unhappy and you're not eating an excess that got you in this mess in the first place.

I'm speaking through science not experience because like many of you when I started MFP it started me out below my BMR...couldn't sustain it. I changed some settings and hopefully things will change. Heck I might have lost weight if I wasn't so damn hangry all the time :P

petd

Ok, maybe I am being dense, but surely we are ALL eating below our BMR to lose weight?

MFP calculated my BMR as X. Then tells me I need to eat X - 500cals to lose 1lb per week. So I am eating below my BMR? And this is bad?

Am confused...:embarassed:

taylorblues

bump..........want to follow this discussion later.

kenny_johnson

There's also an article in here regarding loss of lean mass on a high deficit - http://www.myfitnesspal.com/topics/show/424130-why-you-don-t-want-to-set-your-cal-deficit-too-high

This can be staved off with eating more protein, but lets face it, not that many of the people eating under BMR are getting 1g of protein per lb of lean mass.

Low-carbers might. But I get the point. I didn't get to read the full article (I only saw the abstract), but it looks interesting, thanks. This seemed to be more about how quickly someone should lose weight, rather than eating below their BMR. It concluded with losing no more than .7% of your body weight each week. It was specifically looking at athletes, but may apply to others as well. Not sure if the morbidly obese (BMI > 40)., like myself are in the same boat. But even that study shows I could lose about 2.4 pounds of body weight each week to maintain as much lean body mass as possible. And to accomplish that, I can eat below my BMR. It would be about 1250 calorie deficit for me.