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

 
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April 11, 2012 3:22 PM
For me, the TDEE/BMR business is extremely confusing.
According to the BMR calculator here, I should only be eating a bit over 1300 calories per day?
I went to a TDEE calculator and it says my TDEE is 2017.
I am currently aiming for 1500 calories a day.

From what others are saying, I think I'm doing it right. You are supposed to eat between your TDEE and BMR, correct?

I'm not in a rush to lose weight overnight, btw, I just want a sustainable, healthy lifestyle that gives me the energy for day-to-day activities and exercise.
  2890974
April 11, 2012 3:24 PM
QUOTE:

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.......


Like this. Great explanation.
  15852058
April 11, 2012 3:25 PM
Simply put....if you lose eating consistently way below your BMR you are burning muscle along with fat. If you burn muscle, you are slowing down your metabolism as you will need less calories to survive because you have less muscle. You will then most likely gain everything you lost back plus some after you stop starving yourself because your metabolism will be shot which starts the wicked cycle that many of us here on this site have fallen into.....eat, get fat, starve, eat, get fatter, starve again.......blah!

Edited after posting

So....figure out your BMR (on line calculators are not always accurate....you are better off going to get it checked at a sports lab)....then, figure out your TDEE.....whatever you eat below your TDEE will be your calorie deficit. Just don't eat below your BMR. So for me, my usual TDEE is 2750 (I wear a bodymedia to be more accurate)....my BMR is 1730. I usually aim to eat around 2000 calories which is 750 calories below my TDEE. So far so good.....
Edited by jenluvsushi On April 11, 2012 3:34 PM
  4192509
April 11, 2012 3:26 PM
I think that what that post failed to point out is that you want to eat below your BMR plus TDEE. Also, your body will not eat it's own muscle if you eat below your BMR...it will burn a 2:1 ration of fat and muscle without activity. You can rebuild muscle once you have lost weight, but the most efficient way to lose weight is through both calorie reduction and excercise.

For example, my BMR with TDEE while nothing whatsoever is 2322.42 calories per day. That is sitting on my butt doing nothing all day long. If I eat below that, for every three pounds I lose, one will be of muscle, and two will be of fat. Now, since I actually work out about 3-5 days a week, my BMR with TDEE is actually 2999.79 calories per day. Since I am also working out, I will lose less muscle than the 2:1 ration, but it will still be both.

Now, I have lost 189 lbs. That means theoretically that I have lost 126 lbs of fat and 63 lbs of fat. Heres the problem of that theory of losing muscle...since I have begun losing weight, I have gone down about 10% body fat. That means I have more lean muscle than fat than I used to have.

Once I reach my goal weight, I will go back to my BMR with TDEE for calories, but I can also continue with strength training to build more muscle and lose more bodyfat. At that point, I will be replacing a pound of fat with a pound of muscle which will reduce my body size and my body fat since fat takes up more space than muscle.

I hope this helps you to understand why that previous comment is not entirely true.
April 11, 2012 3:26 PM
im gonna take a stab in the dark, if you are not eating enough then you probably wont be able to gain muscle. if you 'go into starvation mode' you will loose weight. if you go from eating nothing to eating badly then your body may store all the calories up incase you starve it again.

i very much doubt that if u eat below you bmr you will turn into bone and fat?? still be over weight but have no muscle strength??


i would guess eating below your bmr means that if you go back to your old habit then you would perhaps put the weight on faster than if you had lost the weight slowly eating more calories??

im probably about to be proven wrong but that is how i understand it without getting to scientific lol
  20334097
April 11, 2012 3:27 PM
QUOTE:

Hi all
iI need some advice, I am really confused now...I am only 4ft 10 and weigh 50 kg and my BMI is currently 23.5 and would like it to be lower. My BMR according to MFP is 1332 and I am sedentary but walk about 3x a week so my TDEE is 1410 kcal's, so to lose weight I know you should eat 500 less to lose 1lb per week, but I know its bad to eat under 1000 and so I try and aim for 1050 net, but now I'm confused, should i be aiming for more??
I don't want to lose 0.5lb per week, i am going on holiday in 6 weeks and want to wear a bikini and feel confident, so far i have lost 2kg in 4 weeks at this calorie amount and am happy with it.
thanks


Your NET calories is what is important to lose weight, not your INTAKE. Your NET cals = your TDEE (Total Daily Energy Expenditure) - your defecit + plus exercise.

For example: if your TDEE* is 1800
You want to lose 1 lb a week, your NET has to be 1300, or a 500 cal defecit from your TDEE. You can create this defecit with exercise OR eating:
Intake 1300 - no exercise = 1300 net
Intake 1800 - 500 exercise = 1300 net
Intake 1500 - 200 exercise = 1300 net

You have to make sure you are INTAKING enough for your body, so the less you have to lose, the less you can rely on your eating alone creating the defecit and the more you have to incorporate exercise to get to your net but still be intaking enough. MFP's intake minimum is 1,200, this isn't necessarily a hard and fast rule for some of us smaller women.

If your sedenatry TDEE is 1410 and you want to lose a pound a week, you are going to need to create a 500 cal defecit either from eating or exercising, which means your NET will have to be at 910, although your INTAKE should be higher. I would suggest (without knowing much about you) to eat at 1,200 and exercise 210 cals off a day (and don't eat them back), which would create a 910 NET. YES, this net is below your BMR, but when you only have a few lbs to lose, this can't be helped. You only have to worry about damaging your metabolism if you eat significantly below your BMR for awhile, and from what I can tell about your post you probably don't have very many lbs to lose so they should be gone in a few weeks.

Make sure you are accurate in your burns like with using a Heart Rate Monitor, treadmills and average calculators can't be trusted.
Edited by jsapninz On April 11, 2012 3:31 PM
April 11, 2012 3:28 PM
QUOTE:

Simply put....if you lose eating consistently way below your BMR you are burning muscle. If you burn muscle, you are slowing down your metabolism as you will need less calories to survive because you have less muscle. You will then most likely gain everything you lost back plus some after you stop starving yourself because your metabolism will be shot which starts the wicked cycle that many of us here on this site have fallen into.....eat, get fat, starve, eat, get fatter, starve again.......blah!


Makes sense.
  2890974
April 11, 2012 3:29 PM
QUOTE:

QUOTE:

QUOTE:

Good question. I don't think that your body is breaking down only fat if you eat above your BMR and only muscle if you eat below it, I think it is a mix of both either way.

That point aside, why would you want to eat fewer calories than your body needs for the most basic functioning?


Why not? You body can get calories from fat stores, its not going to just shut down if you eat under your BMR


YOUR BODY CAN'T LIVE ON JUST FAT. It needs other things like vitamins, calcium, iron, etc.
Your body WILL shut down eventually. Not from slightly eating under your BMR, but from severly doing so.


No doubt that one needs to get enough vitamins and minerals. That is what the 1200 calorie per day minimum is for.

But I imagine that in the original poster's case, vitamins and minerals are not an issue. If he is asking out of practical interest, not just scientific curiosity, I'd imagine that he's trying to decide whether to eat his BMR of about 2500 or with a 1000 deficit, which would be about 2100. Unless he's eating pure junk, either is going be plenty to give him sufficient vitamins and minerals.
Edited by treetop57 On April 11, 2012 3:38 PM
  13285248
April 11, 2012 3:34 PM
This seems ridiculous. As long as you get enough protein in your diet you won't lose much muscle eating under BMR.
  9633020
April 11, 2012 3:41 PM
If there is a general acceptance that BMR is what it is (and I think there is enough science to back it up) then isn't it just common sense that eating less than that is a bad thing?
  17948830
April 11, 2012 3:48 PM
Human beings are, at their core, animals. Our bodies are made for survival. The reason it will start to consume muscle before fat, when faced with a large caloric deficit, is for survival. As many posters have pointed out, muscle burns more calories than fat, and so getting rid of it is the most efficient step to take. The other reason is that fat is an insulator. In the days before modern homes and food supplies, staying warm was just as important as staying fed (maybe even more so, since you can freeze to death a lot faster than you can starve to death). Our modern way of living evolved in a very short amount of time, whereas our bodies have not.

Some posters have mentioned holocaust survivors as evidence that "starvation mode" is a myth, because they have all, obviously, lost a lot of weight-- even those who didn't have any to lose. What they fail to realize, however, is that holocaust survivors did not lose that weight on their own. They were deprived of food, and their bodies essentially consumed themselves. Without being held in captivity and starved to death, only someone w/ a serious eating disorder could ever "hope" to lose weight that way. Hunger is painful, and no one could hold out for months/years (depending on how much you have to lose) and not eat what is readily available to them.
  20194529
April 11, 2012 3:49 PM
QUOTE:
If there is a general acceptance that BMR is what it is (and I think there is enough science to back it up) then isn't it just common sense that eating less than that is a bad thing?


And common sense used to say that bad air caused malaria and witches caused plague. Neither turned out to be true.
Edited by treetop57 On April 11, 2012 3:50 PM
  13285248
April 11, 2012 3:51 PM
QUOTE:

And common sense used to say that bad air caused malaria and witches caused plague. Neither turned out to be true.


Again, the difference being that common sense in my statement is being applied to to an accepted scientific calculation. Apples to oranges much?
Edited by Lane1012 On April 11, 2012 3:53 PM
  17948830
April 11, 2012 3:53 PM
Both are delicious!
  13285248
April 11, 2012 3:53 PM
QUOTE:

Both are delicious!


no argument there!
  17948830
April 11, 2012 3:54 PM
QUOTE:

QUOTE:

QUOTE:

QUOTE:

Good question. I don't think that your body is breaking down only fat if you eat above your BMR and only muscle if you eat below it, I think it is a mix of both either way.

That point aside, why would you want to eat fewer calories than your body needs for the most basic functioning?


Why not? You body can get calories from fat stores, its not going to just shut down if you eat under your BMR


YOUR BODY CAN'T LIVE ON JUST FAT. It needs other things like vitamins, calcium, iron, etc.
Your body WILL shut down eventually. Not from slightly eating under your BMR, but from severly doing so.


No doubt that one needs to get enough vitamins and minerals. That is what the 1200 calorie per day minimum is for.

But I imagine that in the original poster's case, vitamins and minerals are not an issue. If he is asking out of practical interest, not just scientific curiosity, I'd imagine that he's trying to decide whether to eat his BMR of about 2500 or with a 1000 deficit, which would be about 2100. Unless he's eating pure junk, either is going be plenty to give him sufficient vitamins and minerals.


Let's give my numbers. My BMR according to MFP is 2,547. However, before exercise, MFP assigns me 2180 calories to lose 2 pounds a week. This is below my BMR.

Many sites say that I can lose as much as 1% of my body weight, so I feel like I can safely lose 3.5 pounds a week (that's decreasing as I lose weight -- as of today it'd actually be 3.36). For good or bad, I'm currently averaging more than that, but it includes my first week of a 9 pound loss which probably included a lot of water.

What I've been trying to do is leave an average of 500 calories remaining after my exercise each day to average a 3 pound weight loss. I accomplish this by averaging between 2000-2400 calories a day and exercise (Power 90 plus walking). I've never eaten my BMR since I started here. I don't feel deprived or out of energy. I'm pretty sure I'm getting enough nutrients.

But according to the "You have to eat at least your BMR" people, I should be eating a minimum of 2547 calories a day and then even more if I'm exercising. This would not give me the 1000-1500 calorie deficit I need to lose 2-3 pounds a week (which again, I think is safe).
  18915410
April 11, 2012 3:57 PM
QUOTE:

If there is a general acceptance that BMR is what it is (and I think there is enough science to back it up) then isn't it just common sense that eating less than that is a bad thing?


No, because as I've stated ad naseum -- you HAVE TO put your body into energy deficiency to lose weight. Whether that's below BMR or above it.
  18915410
April 11, 2012 3:57 PM
QUOTE:

QUOTE:

Here is a nicer one:

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


Figure 4 shows that even on 800 calorie/day diets, the weight loss was overwhelmingly water and fat. During the low-carb phase, the loss was 61.2% water, 35% fat, and 3.8% protein. During the mixed phase, the loss was smaller, mostly because less water was lost: 37.1% water, 59.5% fat, and 3.4% protein.

The subjects all had BMRs much greater than 800 calories/day. Table 2 shows BMRs ranging from 1555 to 2380, two or three times the 800 calories they ate during the experiment.

Table 2 also show the changes in weight and changes in BMR. For half of the six subjects, the two track exactly. (In other words, the BMR reduction was simply due to weight loss.) In two subjects, the BMR reduction was about 50% higher than you'd expect just from the weight loss. And in one subject, the BMR increased even though the weight was down by 13%, the exact opposite of the so-called starvation mode!

I certainly don't see that study as supporting either of these propositions:

1. Eating less than your BMR will cause you to lose muscle instead of fat.
2. Eating less than your BMR will slow down your metabolism and put you in "starvation mode."

Perhaps the second proposition was true in 2 of the 6 subjects. Not true in the other 4.


Well, no where did I state that you would lose muscles "instead" of fat. In all posts I stated that you lose both whatever you do. But that study does indeed show the ratios of loss, that you can then compare to other studies, like the second one I linked in that post. Of course you will lose fat, and tons of it on a diet like that, but the ratio of muscles you lose is higher that it needs to be too. And as far as I know, no study has been done that directly compares such samples, you have to check body composition weight loss from different studies, and that's not ideal.

Another key part that is left out of every low cal diet study I have read so far is the part where you are supposed to go back to your normal routine. Not because you give up, but because you actually did it, you are at your goal weight, congratulations, now what? What I have read on that subject is that less than 1% of people on diets keep the weight off in the long run. Which has lead me to rather change my activity level, and eat above my BMR to sustain it.

Anyway, thanks for sharing your replies and challenging my opinion on this :p There certainly is a lack of studies on the exact subject of "What happens to people when they eat X cals below their BMR for Y months", but every study I have seen so far seems to point that it would not be the ideal way to go.
  18610286
April 11, 2012 3:57 PM
QUOTE:

Human beings are, at their core, animals. Our bodies are made for survival. The reason it will start to consume muscle before fat, when faced with a large caloric deficit, is for survival. As many posters have pointed out, muscle burns more calories than fat, and so getting rid of it is the most efficient step to take. The other reason is that fat is an insulator. In the days before modern homes and food supplies, staying warm was just as important as staying fed (maybe even more so, since you can freeze to death a lot faster than you can starve to death). Our modern way of living evolved in a very short amount of time, whereas our bodies have not.


Ok.. Then why is a calorie deficit above BMR different than one below it? Wouldn't both eat muscle first?
  18915410
April 11, 2012 3:58 PM
QUOTE:

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.

???
actually, just a quick search on ncbi returned some "non-existent" studies. for example:
http://www.ncbi.nlm.nih.gov/pubmed/18842775

pay attention to "total energy expenditure -- in particular, energy expenditure at low levels of physical activity -- is lower than predicted by actual changes in body weight and composition."

and if you go through reference list of this paper you'll find more.

I don't understand how people throw around statements like "there are no studies supporting..." without checking themselves if this was really true...
  9876022
April 11, 2012 4:00 PM
QUOTE:

Sounds bogus to me, I believe its just made up and spread over and over on the MFP forums.

Why would your body attack muscle first instead of fat for energy? That would be quite stupid

I can see it using muscle for protein it needs, but not energy.

I don't believe your BMR is the magical cut off for your body to start eating your muscle tissue, if someone can prove to me otherwise I stand corrected

It burns muscle first when in too great a defecit because muscle requires energy to sustain, whereas fat doesn't, and doesn't give two craps about how your muscles look - it's designed to keep you alive, not pretty.

Eat at a deficit to your TDEE and you will lose weight. Eat at too great a deficit for your body to sustain, and you will lose the wrong kind of weight. Eating above your BMR ensures your body has enough energy and nutrition to sustain lean mass and to burn the less efficient fuel - fat.
Edited by ironanimal On April 11, 2012 4:03 PM
April 11, 2012 4:01 PM
QUOTE:

QUOTE:

If there is a general acceptance that BMR is what it is (and I think there is enough science to back it up) then isn't it just common sense that eating less than that is a bad thing?


No, because as I've stated ad naseum -- you HAVE TO put your body into energy deficiency to lose weight. Whether that's below BMR or above it.


You're ignoring the point made earlier about people who have a lot of weigh to lose. Anyone whose BMR is where yours is and who can eat 2000+ calories per day and still be at a "Deficit" is obviously going to be able to get the nutrients they need from all the food they're allowed to eat. This is not the case for people who are much closer to their healthy goal weight and have a BMR around 1500. If they deficit the 500 that you do - they're then expected to survive (in a healthy way) off of 500 calories a day? NOT going to happen. The body will start to shut down and whenever goal weight IS reached and maintenance calories (i.e. TDEE) is resumed, all of a sudden the weight will pop right back on, because the body is singing: YAY FAT! STORE IT! KEEP IT! DON'T LOSE IT AGAIN BECAUSE WE NEED IT!
  12824789
April 11, 2012 4:03 PM
QUOTE:

QUOTE:

QUOTE:

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.

The one BIG point that you didn't take into account about starvation mode in the haulocoust is that those victiums never had the opportunity to eat any thing else. What happens with people that have access to food looks something like this: Jane eats 1350 calories a day(her bmr is 1650). For a bit she looses weight supper fast. She notices that she is low on energy and hungry all of the time. All of a sudden she quits loosing. James metabolism has slowed down to meet the 1350 calories a day and her body isn't a fat burning machine. Actually her body is doing it's best to bum as little energy as possible. So Jane knocks her calories down to 1200 the same cycle happens. Now Jane has the chore of eating less, but she is so flipping tired that she dosent have the energy to cook for herself. Jane throws her diet out the window. When she starts eating again her metabolism is so slow it burns as little ass possible and she gains back twice as much weight! And in this whole prosscess she is screwing her hormones so out of whack that shell have to get medical help for it later.

But you guys seem to know it all so go ahead and tell people that it's all just a sham. Go ahead and encurage people to starve themselves and not to eat enuff to have the energy to build lean mucel to help their bodies stay fit long after they have reached a goal. That's way cool!!

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.
  17184719
April 11, 2012 4:04 PM
QUOTE:

QUOTE:

Human beings are, at their core, animals. Our bodies are made for survival. The reason it will start to consume muscle before fat, when faced with a large caloric deficit, is for survival. As many posters have pointed out, muscle burns more calories than fat, and so getting rid of it is the most efficient step to take. The other reason is that fat is an insulator. In the days before modern homes and food supplies, staying warm was just as important as staying fed (maybe even more so, since you can freeze to death a lot faster than you can starve to death). Our modern way of living evolved in a very short amount of time, whereas our bodies have not.


Ok.. Then why is a calorie deficit above BMR different than one below it? Wouldn't both eat muscle first?


Not sure you understand the difference between BRM and TDEE?

BMR = The calories your body needs to survive (in a healthy way) just lying down doing NOTHING. Breathing and being still. Not getting up to go the the bathroom. Not chewing gum. Not lifting up the remote control and changing channels.

TDEE = BMR AND all the activity you do all day long, be it exercise, walking to your car, having sex, whatever...

If you eat below BMR, you're not giving your body the MINIMUM it needs on a day-to-day basis, just to exist. You take the deficit from the TDEE because you will still be eating more than enough to survive but less than what you expend overall doing whatever it is you do during the day.
  12824789
April 11, 2012 4:06 PM
QUOTE:

You're ignoring the point made earlier about people who have a lot of weigh to lose. Anyone whose BMR is where yours is and who can eat 2000+ calories per day and still be at a "Deficit" is obviously going to be able to get the nutrients they need from all the food they're allowed to eat. This is not the case for people who are much closer to their healthy goal weight and have a BMR around 1500. If they deficit the 500 that you do - they're then expected to survive (in a healthy way) off of 500 calories a day? NOT going to happen. The body will start to shut down and whenever goal weight IS reached and maintenance calories (i.e. TDEE) is resumed, all of a sudden the weight will pop right back on, because the body is singing: YAY FAT! STORE IT! KEEP IT! DON'T LOSE IT AGAIN BECAUSE WE NEED IT!


But you've ignored where i've said that I thing a very large caloric deficit is unhealthy. I understand that as someone who has a lot of weight to lose, I'm in a different boat than someone who has to lose 20 pounds.

The problem is, the "Do not eat below your BMR" is a general guideline that "prescribed" to everyone. That's the whole mantra of fat2fit radio, for example. They even assign your calorie consumption based on this assumption -- no matter what your size is.
  18915410

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