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mgrav95
04-01-2014, 07:20 PM
Hey guys
I have a pretty specific question, hopefully someone has studies/information regarding this topic.

I'm wondering how quickly a persons metabolic rate adjusts in response to the amount of calories consumed daily. Obviously it would vary from person to person but I'm sure on average there's a common timeline.

More specifically, let's say a persons BMR was 2000 calories and taken into account their activity levels their maintenance was 2500. If this person was to "crash diet" and consume around 1500 - 1800 calories daily, how quickly would their BMR drop down from it's normal levels?

So shortly put, how long is it considered "safe" to eat at a level of calories far below your BMR? Of course I know this isn't a healthy way of dieting in any sense and the slower your calories are reduced the better! I'm just curious how long this could be sustained?

Thanks guys

WonderPug
04-01-2014, 09:53 PM
Downregulation can occur rapidly in response to acute caloric restriction and can persist during the duration of such restriction, but such downregulation is typically restricted to ~10% to, at most, 20% (from baseline BMR).

THSP
04-01-2014, 10:19 PM
Hey guys
I have a pretty specific question, hopefully someone has studies/information regarding this topic.

I'm wondering how quickly a persons metabolic rate adjusts in response to the amount of calories consumed daily. Obviously it would vary from person to person but I'm sure on average there's a common timeline.

More specifically, let's say a persons BMR was 2000 calories and taken into account their activity levels their maintenance was 2500. If this person was to "crash diet" and consume around 1500 - 1800 calories daily, how quickly would their BMR drop down from it's normal levels?

So shortly put, how long is it considered "safe" to eat at a level of calories far below your BMR? Of course I know this isn't a healthy way of dieting in any sense and the slower your calories are reduced the better! I'm just curious how long this could be sustained?

Thanks guys

I've done several experiments on BMR and mine will adjust within 36 hours. It's mainly a function of glycogen depletion so whether or not it's achieved with a low calorie diet or fasting it bottoms out around 1,550 calories. Of course this means the longer you prolong the glycogen depletion the slower it will drop. Conversely to go back up glycogen stores need to be replenished so it will start going up readily but take time depending on how much you're refeeding. My BMR is around 1,900 calories calculated and is measured between 1,550 and 3,000 calories.

It's "safe" to eat far below your BMR for an extended amount of time. I've even done a water fast for a week. In a different month I fasted for 11 days total. My BMR still will go up to 3,000 calories on a 4,500 calorie diet. The concept of "metabolic damage" is mostly an unscientific speculation; however, Dr. Leibel has found that in the case of formerly obese patients with reduced leptin levels from recent weight loss BMR will remain decreased even upon refeeding. So there is evidence of "metabolic damage", it's just from being obese not from eating patterns. Even he doesn't suggest this drop in BMR is necessarily negative though, just an increase in efficiency...

mgrav95
04-01-2014, 10:59 PM
I've done several experiments on BMR and mine will adjust within 36 hours. It's mainly a function of glycogen depletion so whether or not it's achieved with a low calorie diet or fasting it bottoms out around 1,550 calories. Of course this means the longer you prolong the glycogen depletion the slower it will drop. Conversely to go back up glycogen stores need to be replenished so it will start going up readily but take time depending on how much you're refeeding. My BMR is around 1,900 calories calculated and is measured between 1,550 and 3,000 calories.

It's "safe" to eat far below your BMR for an extended amount of time. I've even done a water fast for a week. In a different month I fasted for 11 days total. My BMR still will go up to 3,000 calories on a 4,500 calorie diet. The concept of "metabolic damage" is mostly an unscientific speculation; however, Dr. Leibel has found that in the case of formerly obese patients with reduced leptin levels from recent weight loss BMR will remain decreased even upon refeeding. So there is evidence of "metabolic damage", it's just from being obese not from eating patterns. Even he doesn't suggest this drop in BMR is necessarily negative though, just an increase in efficiency...


Beautiful reply thank you heaps! Exactly the kind of answer I was looking for!!

WonderPug
04-01-2014, 11:05 PM
I've done several experiments on BMR and mine will adjust within 36 hours. It's mainly a function of glycogen depletion so whether or not it's achieved with a low calorie diet or fasting it bottoms out around 1,550 calories. Of course this means the longer you prolong the glycogen depletion the slower it will drop. Conversely to go back up glycogen stores need to be replenished so it will start going up readily but take time depending on how much you're refeeding. My BMR is around 1,900 calories calculated and is measured between 1,550 and 3,000 calories.

It's "safe" to eat far below your BMR for an extended amount of time. I've even done a water fast for a week. In a different month I fasted for 11 days total. My BMR still will go up to 3,000 calories on a 4,500 calorie diet. The concept of "metabolic damage" is mostly an unscientific speculation; however, Dr. Leibel has found that in the case of formerly obese patients with reduced leptin levels from recent weight loss BMR will remain decreased even upon refeeding. So there is evidence of "metabolic damage", it's just from being obese not from eating patterns. Even he doesn't suggest this drop in BMR is necessarily negative though, just an increase in efficiency...Please ignore ^^^this^^^ utter nonsense

The relevant poster keeps posting deliberately misleading information, I presume to try to mislead people.

MarkoPW
04-01-2014, 11:15 PM
Very interesting topic. I never considered how much I could go below my BMR

As a personal note, sometimes users do not post misleading information on purpose but they are negged by mods anyway. True story.

THSP
04-02-2014, 02:23 AM
Please ignore ^^^this^^^ utter nonsense

The relevant poster keeps posting deliberately misleading information, I presume to try to mislead people.

Do you really have to bold every first sentence you type? WHY DONT YOU JUST DO ALL CAPS AND SAY, "GO F*** YOURSELF", because it's just as effective, scientific, and qualified.

You're a dolt. Why don't you add some relevance to your drabble.