consuming few calories destroys metabolism.. True or a myth?

delgrand · December 2017

I wonder whether the "consuming few calories destroys metabolism" is true or false. Information on the internet contradict each other. I read or hear on a fitness channels that if you eat few calories ( 800 for example) for a long period you will lose weight fast but you will destroy your metabolism and when you eat normally even within the average calories required for people with the same weight, you will gain all the weight back because you destroyed your metabolism. Other sites say that this is a myth .. what should I believe ?

Edit: Please don't take the word "destroyed" literally.

liftingbro · December 2017

It's true in the long term. You don't really "damage" metabolism as much as there is metabolic adaptation.
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People who eat very low calorie levels over a long period of time will tend to have lower BMRs for people of their size.

Don't have links but if you Google merabic adaptation you should find plenty to read.

mmapags · December 2017

Can be true if very low calorie diet is consumed over a long period of time. Google adaptive thermogenesis. And done for long enough, it can cause a permanent down regulation of an individuals metabolism.

It happens to a lesser degree even in the short term soon after we begin calorie restriction. This is a great reason to incorporate periodic refeeds and diet breaks. There is a great thread on doing this here: http://community.myfitnesspal.com/en/discussion/10604863/of-refeeds-and-diet-breaks/p1

In a person functioning normally, adaptations happen both up and down metabolically. Eg. You diet and get some down regulation of metabolism. You eat at or above maintenance after dieting and you get up regulation to normal metabolism (for the individual).

I think what is referred to as a myth is "starvation mode".

ETA: Noel makes a good point. Even with permanent downward adaptations, one's metabolism is not "destroyed" or they are dead.

Unknown · December 2017

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CSARdiver · December 2017

Complete myth.

In the short term think of your metabolism like a fire - the more fuel/food you add, the hotter the fire, the higher the metabolism. The less fuel/food, the lower the fire/lower the metabolism. This is adaptive thermogenesis - short lived (24-72 hours) and trends toward your BMR once complete.

When a 300 lb man loses 150 lbs for a few months his BMR will be marginally less than another 150 lb man of similar height/build. This is another impact of adaptive thermogenesis. The body has grown accustomed to utilizing a set amount of fuel to drive the various metabolic pathways. Adjustments take time and biological systems need this time to adapt.

Biological systems are incredibly efficient and will stop providing energy to those not being used.

deannalfisher · December 2017

CSARdiver wrote: »

Complete myth.

In the short term think of your metabolism like a fire - the more fuel/food you add, the hotter the fire, the higher the metabolism. The less fuel/food, the lower the fire/lower the metabolism. This is adaptive thermogenesis - short lived (24-72 hours) and trends toward your BMR once complete.

When a 300 lb man loses 150 lbs for a few months his BMR will be marginally less than another 150 lb man of similar height/build. This is another impact of adaptive thermogenesis. The body has grown accustomed to utilizing a set amount of fuel to drive the various metabolic pathways. Adjustments take time and biological systems need this time to adapt.

Biological systems are incredibly efficient and will stop providing energy to those not being used.

#scienceFTW

Silentpadna · December 2017

The adaptation thing is real, but not in the sense that your metabolism is "destroyed". It's really a matter of degree. The best way to prevent it is not to crash diet. You should always eat to support activity and stay or get strong. If you are eating at a deficit, unless you are morbidly obese, the smaller the deficit, the smaller the adaptation.

Another point I try to make often is that many, if not most people, have short timelines as a part of their weight-loss goal. This can be counter-productive. I'm no expert, but if I had to do mine over again, I would lose weight slower than I did. And strength train more and earlier in the process.

I still have about 10-15 pounds to go, and I actually plan on that to take 6-8 months to do. And, as another poster has mentioned, there will be periodic refeeds and breaks involved.

Nudgey02 · December 2017

Have a look at stuff by Lyle Macdonald, there are some good podcasts on you tube featuring him. It is all to do with how your body adapts and how the hormones change when you eat low calorie or low carb diets for a long time. He suggests that you need to refeed at maintenance or above for 2 - 10 days to get everything back to normal and then you will start losing again when in deficit. It shouldn't be a big deficit though.

cmriverside · December 2017

Here's a really well-researched and well-discussed thread on this by one of our resident PhDs.

Starvation Mode Adaptive Thermogenesis and Weight Loss

It's in the stickies in General Weight Loss. You might want to take a look at it - and all the sitickies.

Lisa8823168 · December 2017

I have a deeper question....and several of you are more expert than I on these topics...

How do thyroid disorders, diabetic concerns and hormone changes (menopause for one example), affect body chemistry and metabolism? When people are in various ranges or on the threshold of any of these situations (maybe not yet under drug therapy)...verses being the "average" person without these concerns, would there be metabolism affects? When medications are used to treat these disorders, and fluctuations in the body happen throughout the day/dosing cycle, would metabolism be affected? What about metabolism is or is not speaking to these other body disorders?

I would think, but I don't know, that metabolism would be affected by your body if you have a thyroid not working correctly (hypo or hyper) or have difficulties processing glucose or depleting estrogen in your system has your hormones crazy. What about people with various stages of kidney function disorders? Would a malfunctioning kidney affect your metabolism? Why or why not?

Since we are all not blessed with being the "average" healthy person that mainstream medical community bases recommendations on, what are the concerns? Don't many of these items play a role in a metabolism functioning normally? Do drugs fix everything? If yes, why would, people taking medications for these issues have to be monitored and meds adjusted periodically when threshold are exceeded?

What exactly in a bodies chemistry makes up the metabolism and how it burns calories? How would it (metabolism) work or not (interact or use or depend on or rely-pick what ever word you like) on areas mentioned above?

Just seems like our bodies are designed to work a certain way and deviation (like disorders listed above or radical diet plans) affect efficiency of all sorts of body functions at some point. For example, a diabetic has wound healing issues or diabetic nerve pain in their feet. Therefore, the actual disorder is affecting the body in multiple ways. Why not they metabolism?

Just my deeper thoughts on the possibilities of have a problem with metabolism that could mean your not yet in the cemetery.

CarvedTones · December 2017

Disclaimer - I have problems with EDs and I am actively working on them and I am currently eating at a healthy level. I have cycled over the years, bingeing to get fat and then going overboard with cutting back to take it off. I am now trying to break the cycle.

Now, having said all that, I have some relevant experience. The most recent one was 2 months of losing about a half pound a day. This is stupid to do and I am not recommending it. But I was eating at the same level and losing at roughly the same level all the way through (it tapered off slightly as I weighed less), so two months wasn't long enough to cause it. A few years ago I went about 4 months of under eating to take about 60 off and it didn't kill my metabolism. Again, I absolutely do not recommend that anyone, including myself, try this idiotic way to lose weight. I lost some lean body mass with the fat. But I did not have any major change in metabolism.

EDIT to add - during the 4 month one, I was running and I did increase the miles I ran per week during the 4 month stretch. During the 2 month stretch, I was doing no exercise.

AnnPT77 · December 2017

Nontecnically, you could think of it this way:

You go on a crazy low calorie diet. Your energy level suffers. Your workouts suffer: Less intensity. You do less than usual when it comes to chores, hobbies, work, other activities, because you're vaguely tired, draggy. Maybe nothing big changes, but lots of little things do, maybe almost unnoticed. These things become your daily habits. When you go back to adequate calories, these are still habits.

On the inside, invisible, your internal body processes do the same thing, slow down a little. It's an adaptation to reduced calories. That adaptation, too, may become "habitual".

Anecdotally, some people seem to up-regulate activity (change unconscious habits) more automatically, compared to others, once calorie deficit ends. It wouldn't be too surprising if being "on a diet" too long, or too extremely, might influence how quickly and fully any particular person recovers.

One thing: This down-regulation of internal/external activity never gets so low that weight loss becomes impossible, unless we're dead. If ultra low calories for long periods stopped weight loss, no one would ever starve to death. Sadly, people starve to death every day.

CSARdiver · December 2017

lisawolfinger wrote: »

I have a deeper question....and several of you are more expert than I on these topics...

How do thyroid disorders, diabetic concerns and hormone changes (menopause for one example), affect body chemistry and metabolism? When people are in various ranges or on the threshold of any of these situations (maybe not yet under drug therapy)...verses being the "average" person without these concerns, would there be metabolism affects? When medications are used to treat these disorders, and fluctuations in the body happen throughout the day/dosing cycle, would metabolism be affected? What about metabolism is or is not speaking to these other body disorders?

I would think, but I don't know, that metabolism would be affected by your body if you have a thyroid not working correctly (hypo or hyper) or have difficulties processing glucose or depleting estrogen in your system has your hormones crazy. What about people with various stages of kidney function disorders? Would a malfunctioning kidney affect your metabolism? Why or why not?

Since we are all not blessed with being the "average" healthy person that mainstream medical community bases recommendations on, what are the concerns? Don't many of these items play a role in a metabolism functioning normally? Do drugs fix everything? If yes, why would, people taking medications for these issues have to be monitored and meds adjusted periodically when threshold are exceeded?

What exactly in a bodies chemistry makes up the metabolism and how it burns calories? How would it (metabolism) work or not (interact or use or depend on or rely-pick what ever word you like) on areas mentioned above?

Just seems like our bodies are designed to work a certain way and deviation (like disorders listed above or radical diet plans) affect efficiency of all sorts of body functions at some point. For example, a diabetic has wound healing issues or diabetic nerve pain in their feet. Therefore, the actual disorder is affecting the body in multiple ways. Why not they metabolism?

Just my deeper thoughts on the possibilities of have a problem with metabolism that could mean your not yet in the cemetery.

Metabolic disorders impact Resting Energy Expenditure (REE) by ~5% in the most extreme conditions. This is tracked by testing patients without a thyroid gland and moving from a treated state to an untreated state. Full disclosure I had a total thyroidectomy and on 175/200 mcg Synthroid alt/day and my BMR is nearly identical to any other 46 year old male with my height/weight.

Dramatic shifts in hormones cause cellular uptake of water - water weight. This is a quick action and natural defensive mechanism - very fleeting and will trend to normal over 5-7 days.

What hormones do impact are satiety and appetite signals, so many who are hypothyroid tend to eat without ever really feeling full or satiated.

Drugs are nothing more than mitigation tactics. The root cause is behavior. Your weight is largely an output of your behavior. Like every mitigation tactic there is an inherent risk and reward.

There are a multitude of factors influencing metabolism, but the greatest are physical work (caloric output) and fuel intake (caloric intake). There are a number of secondary and lower tier factors, but having minimal impact.

delgrand · December 2017

Thanks everyone for the new information.

Lisa8823168 · December 2017

I think there is more to it but then I have a family history which provides some unusual education. I encourage everyone to research MITOCHONDRIA function. It takes about 3000 genes to make a mitochondrion.

Conventional teaching in biology and medicine is that mitochondria function only as “energy factories” for the cell. This is over-simplification, slowing progress and research toward understanding the biology underlying mitochondrial disease. Though found most common in children, adult onset is increasing.

Without going to extensive detail, Mitochondria contain the rate-limiting enzymes for pyrimidine biosynthesis (dihydroorotate dehydrogenase) and heme synthesis (d-amino levulinic acid synthetase) required to make hemoglobin. In the liver, mitochondria are specialized to detoxify ammonia in the urea cycle. Mitochondria are also required for cholesterol metabolism, for estrogen and testosterone synthesis, for neurotransmitter metabolism, and for free radical production and detoxification. They do all this in addition to breaking down (oxidizing) the fat, protein, and carbohydrates we eat and drink.

Because mitochondria perform so many different functions in different tissues, there are literally hundreds of different mitochondrial diseases. Each disorder produces a spectrum of abnormalities that can be confusing to both patients and physicians in early stages of diagnosis.

Google it...draw your own conclusion but I feel it can feed a metabolic problem in people without shutting down organs and killing us...diagnosis is difficult but doesn't mean it is not a real thing.

consuming few calories destroys metabolism.. True or a myth?

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