Why not eat below BMR?

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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 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.

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.

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.

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.

you could die

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

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.

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.

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.

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.

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.

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).