What are the Metabolism Myths/Truths
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leanjogreen18
Posts: 2,492 Member
some of you more educated ones out there ELI5. I think I know that our RMR decreases 20-30% after a period of deficit but is there any other slowing down. Eating too few calories? I've tried researching and honestly some of the acronyms and scientific terms are over my head.
Basically I see people say "maybe my metabolism slowed from not eating enough". Is this true even after a sustained deficit?
I ask because I'm
5'4
50
CW 202
Walk approx 6-8 miles a week
I'm eating average daily 1250 cal (I eat 3 days 1250, 1 day 1100, 1 day 1000, 1 day 1300 and 1 day 1500 rounded numbers) and will be eating this deficit until I get super close to goal weight next summer.
I'm so confused by all the crap out there and the actual studies are hard for me to understand.
Thanks in advance.
Basically I see people say "maybe my metabolism slowed from not eating enough". Is this true even after a sustained deficit?
I ask because I'm
5'4
50
CW 202
Walk approx 6-8 miles a week
I'm eating average daily 1250 cal (I eat 3 days 1250, 1 day 1100, 1 day 1000, 1 day 1300 and 1 day 1500 rounded numbers) and will be eating this deficit until I get super close to goal weight next summer.
I'm so confused by all the crap out there and the actual studies are hard for me to understand.
Thanks in advance.
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Replies
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There is such a thing as the body adapting to a decrease in weight, which is why it's necessary to lower our calorie allotment every 10lbs, however, its often such a low amount that the average person will not notice. What you are descri big, however, is the concept of starvation mode, which does not exist. I'm sure someone will come in with the science because I just took NyQuil and can't even remember the term describing adaptation despite talking about it many times before.
Essentially switching your intake daily will do nothing for your metabolism. It won't "trick" or "reset" it. Not in that short amount of time. If it's something you prefer doing, go ahead. But it won't provide any additional benefits to losing weight beyond the calorie deficit.0 -
If you're talking about eating at a reasonable deficit, no it will not shut your body down. However, if you do only 500 calorie meals every day for at least 6 months - 1 year straight, then yes it will affect your metabolism because your body was forced into the extremes. If you follow the goals set by MFP for you, your body will be fine, so you don't have to worry.0
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Lyle McDonald is a really good source on this.
http://www.bodyrecomposition.com/fat-loss/lean-body-mass-maintenance-and-metabolic-rate-slowdown-qa.html/Studies have repeatedly shown that individuals who have been dieted down to a given weight will have a lower than predicted metabolic rate compared to someone who didn’t diet to that weight. That is, someone who ‘naturally’ weighs 200 pounds will have a higher total energy expenditure than someone who dieted down to 200 pounds.
So what’s causing this reduction in total energy expenditure. A majority of the ‘metabolic slowdown’ that occurs is due simply to the loss of body mass. Because larger bodies burn more calories (both at rest and during activities) and smaller bodies burn less.
But that’s not the only cause of metabolic slowdown here. There is also an adaptive component of metabolic rate slowdown that is mediated by changes in hormones: leptin, insulin, thyroid, catecholamines. As these change (decrease) on a diet, you find that tissues burn fewer calories per unit mass. I’d mention that not all studies find this, about half do and half don’t. That is, your assumption that a given body composition always burns the identical number of calories on a day to day basis isn’t entirely correct.
Of course, an important question is how much of a change this amounts to. During active weight loss, the impact is relatively greater (because hormones tend to be more greatly affected); at weight maintenance (once a person has stabilized), the impact isn’t huge. In some studies of the post-obese (folks who have been dieted down and maintained at that weight) show a relatively modest 5% or so reduction in RMR. The effect exists but is not massive; it’s also highly variable, with people showing relatively more or less of an effect.
There is also evidence that individuals move around less when they lose/are losing weight. As James Krieger recently wrote on his Weightology.net website, it looks like changes in activity (especially NEAT) are the far larger contribution to the reduction in overall energy expenditure on a day to day basis; the number of calories burned in that activity also appear to be reduced due to improved muscular efficiency.
In that study, decreases in RMR were about 150 calories per day but reductions in activity expenditure were up in the 300 calorie plus range with the total effect being over 400 calories. This is likely why daily activity has such a profound impact on weight maintenance as I discussed in Exercise and Weight/Fat Loss Part 2: since the body is ‘automatically’ decreasing activity energy expenditure, you have to make up for it.
It should be noted that in what I've seen of the studies that showed that 20-30% adaptive drop in RMR, all of the subjects were doing a VLCD that had very low protein. I tend to think the figures quoted here by McDonald are more in line with what people eating a higher amount of protein, who also get some exercise, and who use a sensible deficit might experience.4 -
The info about my zig zagging, that was just to let everyone know how I will have a sustained deficit for the next year. Forget zig zagging I'm doing that based on leptin levels and having a variety instead of a stagnant amount, although that's not why I started it.
I'm asking about eating a daily average of 1250 calories for a year. Does that low a deficit cause issues with metabolism? I know the nuetrients could be an issue.1 -
The info about my zig zagging, that was just to let everyone know how I will have a sustained deficit for the next year. Forget zig zagging I'm doing that based on leptin levels and having a variety instead of a stagnant amount, although that's not why I started it.
I'm asking about eating and average of 1250 calories for a year. Does that low a deficit cause issues with metabolism. I know the nuetrients could be an issue.
No, it does not. You should plan diet breaks to replenish various hormone levels and increase likelihood of compliance, though.0 -
You don't think the one day a week eating 1500 is enough to replenish hormones?0
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The info about my zig zagging, that was just to let everyone know how I will have a sustained deficit for the next year. Forget zig zagging I'm doing that based on leptin levels and having a variety instead of a stagnant amount, although that's not why I started it.
I'm asking about eating a daily average of 1250 calories for a year. Does that low a deficit cause issues with metabolism. I know the nuetrients could be an issue.
I'm eating a daily average of 1200, but that is usually increased by at least 150-200 because I work out nearly every day and I have to walk quite a bit (and up & down a hill) from my flat to university. So far no problems. The only real problem that I have is with nutrients, I wasn't eating enough protein, but it's nothing a protein bar or an extra egg can't solve without burning up too much calories.0 -
The info about my zig zagging, that was just to let everyone know how I will have a sustained deficit for the next year. Forget zig zagging I'm doing that based on leptin levels and having a variety instead of a stagnant amount, although that's not why I started it.
I'm asking about eating a daily average of 1250 calories for a year. Does that low a deficit cause issues with metabolism. I know the nuetrients could be an issue.
I'm eating a daily average of 1200, but that is usually increased by at least 150-200 because I work out nearly every day and I have to walk quite a bit (and up & down a hill) from my flat to university. So far no problems. The only real problem that I have is with nutrients, I wasn't eating enough protein, but it's nothing a protein bar or an extra egg can't solve without burning up too much calories.
Ok thanks. I'm eating 40% carbs 30% fat 30% protein without really trying, this is basically how I naturally eat so I think this should be good. The only thing I really changed is having a protein for breakfast which I didn't do in the past because I don't eat meat. I just started eating a few more eggs.0 -
My feeling about it (note I say feeling) is that the reason metabolism "slows down" after being in deficit for a while is that you are literally lower energy, so you fidget less, you move less involuntarily...and thats about it. Most of your BMR is going to be dedicated to basically keeping you alive: keeping your body temperature at 37 degrees C and your brain idling. The amount of energy that takes isn't going to change. There is not going to be some affect from being in deficit that would allow your body to maintain its body temperature for less energy cost.
As for hormonal changes, "starvation mode" and what not...I'm not so sure about those, at least in the context of doing a reasonable diet with a moderate deficit over a prolonged period. In my experience my BMR drops about as I would expect it to as my weight drops but thats about it even if I am dieting 6 months in a row.2 -
I get that as my weight decreases my BMR/RMR will decrease as there is less of me to keep alive therefore less energy is needed. But the myth that I'm damaging my metabolism further still pricks my brain.
I have read that while losing weight, activity is not that important but to maintain that loss it becomes very important and the above Lyle M quote sounds like a confirmation.
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Out of curiosity, how did you calculate your 1250 calorie/day (on average) goal? That seems really low for somebody who weighs over 200 pounds.1
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SusanMFindlay wrote: »Out of curiosity, how did you calculate your 1250 calorie/day (on average) goal? That seems really low for somebody who weighs over 200 pounds.
Mfp gives me that as well as any calculator that I set to loose 2 lbs a week. I put in sedentary which other than the 6-8 miles a week I walk I sit on my butt.
ETA - I loose almost exactly 2 lbs a week as an average (1.8) for the last 4 months so it must be pretty close.
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SusanMFindlay wrote: »Out of curiosity, how did you calculate your 1250 calorie/day (on average) goal? That seems really low for somebody who weighs over 200 pounds.
Mfp gives me that as well as any calculator that I set to loose 2 lbs a week. I put in sedentary which other than the 6-8 miles a week I walk I sit on my butt.
ETA - I loose almost exactly 2 lbs a week as an average (1.8) for the last 4 months so it must be pretty close.
Do you eat back your exercise calories (that 6-8 miles walking)? If not, I wouldn't consider you sedentary.0 -
Carlos_421 wrote: »SusanMFindlay wrote: »Out of curiosity, how did you calculate your 1250 calorie/day (on average) goal? That seems really low for somebody who weighs over 200 pounds.
Mfp gives me that as well as any calculator that I set to loose 2 lbs a week. I put in sedentary which other than the 6-8 miles a week I walk I sit on my butt.
ETA - I loose almost exactly 2 lbs a week as an average (1.8) for the last 4 months so it must be pretty close.
Do you eat back your exercise calories (that 6-8 miles walking)? If not, I wouldn't consider you sedentary.
No I generally don't BUT I do not measure nor weigh my food (yet). I figured the aggressive 2 lb target without measuring or weighing only eyeballing, will only slow the loss instead of stopping it if I don't eyeball close enough. I'm super comfortable in terms of how long it will take me to get to my goal weight at least right now I am:).
I feel like I have enough energy, I'm sleeping good for the first time in a long time. I'm fairly satisfied meaning I know I could eat more if I wanted to go beyond my calorie goal for that day, but no true hunger pains.0 -
Carlos_421 wrote: »SusanMFindlay wrote: »Out of curiosity, how did you calculate your 1250 calorie/day (on average) goal? That seems really low for somebody who weighs over 200 pounds.
Mfp gives me that as well as any calculator that I set to loose 2 lbs a week. I put in sedentary which other than the 6-8 miles a week I walk I sit on my butt.
ETA - I loose almost exactly 2 lbs a week as an average (1.8) for the last 4 months so it must be pretty close.
Do you eat back your exercise calories (that 6-8 miles walking)? If not, I wouldn't consider you sedentary.
If it's even spread out, 6-8 miles/week is about 1 mile/day. "Sedentary" is "less than ~4000 steps/day" and 1 mile is ~2000 steps. So, you *could* walk 1 mile/day and still be sedentary. Depends on what you do the rest of the time.0 -
SusanMFindlay wrote: »Carlos_421 wrote: »SusanMFindlay wrote: »Out of curiosity, how did you calculate your 1250 calorie/day (on average) goal? That seems really low for somebody who weighs over 200 pounds.
Mfp gives me that as well as any calculator that I set to loose 2 lbs a week. I put in sedentary which other than the 6-8 miles a week I walk I sit on my butt.
ETA - I loose almost exactly 2 lbs a week as an average (1.8) for the last 4 months so it must be pretty close.
Do you eat back your exercise calories (that 6-8 miles walking)? If not, I wouldn't consider you sedentary.
If it's even spread out, 6-8 miles/week is about 1 mile/day. "Sedentary" is "less than ~4000 steps/day" and 1 mile is ~2000 steps. So, you *could* walk 1 mile/day and still be sedentary. Depends on what you do the rest of the time.
I am pretty much still sedentary. I walk 2-3 miles 2-3 times a week.0 -
SusanMFindlay wrote: »Carlos_421 wrote: »SusanMFindlay wrote: »Out of curiosity, how did you calculate your 1250 calorie/day (on average) goal? That seems really low for somebody who weighs over 200 pounds.
Mfp gives me that as well as any calculator that I set to loose 2 lbs a week. I put in sedentary which other than the 6-8 miles a week I walk I sit on my butt.
ETA - I loose almost exactly 2 lbs a week as an average (1.8) for the last 4 months so it must be pretty close.
Do you eat back your exercise calories (that 6-8 miles walking)? If not, I wouldn't consider you sedentary.
If it's even spread out, 6-8 miles/week is about 1 mile/day. "Sedentary" is "less than ~4000 steps/day" and 1 mile is ~2000 steps. So, you *could* walk 1 mile/day and still be sedentary. Depends on what you do the rest of the time.
I was assuming this to be "extra" walking, beyond the day to day moving around.0 -
Carlos_421 wrote: »SusanMFindlay wrote: »Carlos_421 wrote: »SusanMFindlay wrote: »Out of curiosity, how did you calculate your 1250 calorie/day (on average) goal? That seems really low for somebody who weighs over 200 pounds.
Mfp gives me that as well as any calculator that I set to loose 2 lbs a week. I put in sedentary which other than the 6-8 miles a week I walk I sit on my butt.
ETA - I loose almost exactly 2 lbs a week as an average (1.8) for the last 4 months so it must be pretty close.
Do you eat back your exercise calories (that 6-8 miles walking)? If not, I wouldn't consider you sedentary.
If it's even spread out, 6-8 miles/week is about 1 mile/day. "Sedentary" is "less than ~4000 steps/day" and 1 mile is ~2000 steps. So, you *could* walk 1 mile/day and still be sedentary. Depends on what you do the rest of the time.
I was assuming this to be "extra" walking, beyond the day to day moving around.
Yes it is extra beyond day to day moving around, but I don't move around that much maybe between 4-6k. I have a tiny house:).
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You don't think the one day a week eating 1500 is enough to replenish hormones?
It's not enough of a real break as your weight drops. The breaks should be more on the order of a week long at maintenance or just slightly below. They are also more about, as Aaron noted, getting your energy level back up.
I'm speaking from experience here.
Take diet breaks.1 -
I get that as my weight decreases my BMR/RMR will decrease as there is less of me to keep alive therefore less energy is needed. But the myth that I'm damaging my metabolism further still pricks my brain.
I have read that while losing weight, activity is not that important but to maintain that loss it becomes very important and the above Lyle M quote sounds like a confirmation.
It's a myth. It really is a myth. I worried a lot about this when I was where you were at too. I researched it a lot too. It's okay. Don't worry. Just keep plugging along, take diet breaks and read Lyle McDonald carefully and follow the links at the bottom of his articles. He doesn't support the idea that you're damaging your metabolism.
And yes, you're correct, activity is extremely important to maintenance. There are, however, successful maintainers who don't exercise. The vast majority of maintainers who exercise find their favorite activity to be brisk walking. That activity doesn't have to be grueling.1
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