6

votes

Are you confused about the metabolic reduction effect of cutting calories too?

Answered on August 19, 2014
Created January 23, 2012 at 4:29 PM

I will start this by saying I am confused, hence the question...

My recent reading includes the report of studies that show that calorie restriction slows the metabolism, such that people who have reduced weight via the method wind up with a Basal Metabolic Rate some 300-400 calories per day lower than before - a key determinant in them putting weight back on again.

Paleo style eating has many benefits, some of which seem to be: . Natural food fats and protein make you feel fuller for longer (than carbs/sugar etc) and therefore you eat less calories naturally, helping to lose weight . Some (Guyenet etc) comment on a similar impact of a lower food reward strategy - ultimately resulting in eating fewer calories . IF has a similar reputation for reducing the hunger and helping to reduce the caloric intake . etc . etc

So why am I confused? Well put simply, what's the difference in the impact on BMR of weight lost due to caloric restriction on "normal" diets vs resulting caloric reduction (even if not intended) on a Paleo style diet?

Or is there no difference? Do Paleo-dieters also have to contend with this BMR impact once weight is lost (albeit maybe easier to then continue eating at this lower level on Paleo) or are there offsetting benefits of Paleo (HGH, testosterone/estrogen etc or something else) that put the BMR back to where it should be even at a lower weight?

EDIT: Is it all about Leptin??? On a "normal" calorie restriction leptin isn't reset whereas on a Paleo diet it is?

792634a784ec6a636c3137d0903e11b4

(1196)

on January 25, 2012
at 12:38 AM

This is really interesting! Nance and Evelyn, you've both answered my question (unwritten, lol) about IF and metabolism. I'm a very hard loser in spite of being obese, and am trying IF as the next stage in my strategy. My sense so far (4 weeks in) is that I'm not triggering the exhaustion or starvation I've experienced using more regular daily caloric restriction. Good to hear that it's likely to be theoretically as well as empirically sound ;)

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 24, 2012
at 09:39 PM

@thhq, you don't think massive weight gain is a good way to build up my leg muscles? This is controversial advice you're giving out here on PH.

Medium avatar

(10611)

on January 24, 2012
at 05:52 PM

And why should we be confined by a single nationality? Those from the UK subsisting on bangers, mash and spotted dick would know that their diet SUKD. And those in the paleo healthy mode would be PHUKD.

Medium avatar

(10611)

on January 24, 2012
at 04:36 PM

My point is more the use of deprecating monikers which reflect a "holier than thou" attitude. I see paleo as a loose practicum, not as a precisionist theology. Walking 10 miles a day, every day, is a more paleo way of living than eating grass fed beef and dietary supplements.

246ebf68e35743f62e5e187891b9cba0

(21420)

on January 24, 2012
at 01:44 PM

thhq - that's just "doing it right". No need for a label. I like the SHAD moniker to separate it from SAD - Seasonal Affective Disorder.

Medium avatar

(10611)

on January 24, 2012
at 01:14 PM

Walk, Paul, walk. My BMR ran true to the correlations throughout my weight loss, and dropped about 500 cal/day for a loss of 50 pounds. Using my calves/thighs (and arms since I started using a walking stick) daily added back that much and more to my metabolism.

Medium avatar

(10611)

on January 24, 2012
at 01:08 PM

So then we have the PHAD (Paleo "Healthy" American Diet)too? Stereotypes begone!

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 24, 2012
at 12:27 PM

Sweet, sounds like a good way to build up my leg muscles.

Medium avatar

(39831)

on January 24, 2012
at 06:56 AM

Yeah, that's what I meant: those fibers are constantly being recruited to heft that weight around. An obese person's calves are a perfect example of this since they'll likely be used a lot even if the person is fairly sedentary. The more active they are, the more muscle. A very large person who isn't totally bed-ridden probably has more muscle in their legs than I do in my entire body.

543a65b3004bf5a51974fbdd60d666bb

(4493)

on January 24, 2012
at 04:15 AM

@PrimalDanny, re your comment "I don't even digest all the calories I eat". You may already be aware of this, but others may not; food calories are an estimate of the product's digestible constituents only. The calorie calculation attempts to take in to account the fact that not all food eaten is actually absorbed by the body. http://en.wikipedia.org/wiki/Food_energy#Nutrition_labels

543a65b3004bf5a51974fbdd60d666bb

(4493)

on January 24, 2012
at 04:09 AM

@PrimalDanny, re your comment "I don't even digest all the calories I eat". You may already be aware of this, but others may not; food calories are an estimate of the product's digestible constituents. The calorie calculation attempts to take in to account the fact that not all food eaten is actually absorbed by the body. http://en.wikipedia.org/wiki/Food_energy#Nutrition_labels

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 24, 2012
at 03:50 AM

Hmmm, good call. I wonder though if the energy needs for new muscle synthesis really compares much to the day-in-day-out needs of the brain, heart, kidney, liver, and GI tract. Another issue: perhaps carrying around a lot of extra fat on the body requires not just the **existence** of those muscles but also their constant **use**, so that's something to work into the comparison. Whereas in the Eades point he was only talking about the existence. Still I'd like to see more numbers. I'll file it away as a mental note. Let me know if you see anything too.

8eade6b270dc874843f74fa599fa8754

(163)

on January 24, 2012
at 02:47 AM

"Standard 'Healthy' American Diet"

Medium avatar

(39831)

on January 24, 2012
at 12:38 AM

Anything beyond what's necessary for survival is expensive. The synthesis of muscle needs to be accounted for, not just the energetic needs of inert muscle.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 11:26 PM

Michael Eades makes a good point about muscle being metabolically expensive, namely that it isn't really. It's in this old post of his: http://www.proteinpower.com/drmike/low-carb-library/are-we-meat-eaters-or-vegetarians-part-ii/ He gets it, more or less, from the Aiello et al. article on the expensive tissue hypothesis. I haven't read a whole lot of work on this, and I don't really feel like hunting right now, but if you think about it, it makes sense. Brain, heart, kidney, liver, and GI tract use up the most. Some more from me here: http://paleohacks.com/questions/27036/

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 11:09 PM

Whether a high-fat or low-fat diet is better for someone trying to lose weight, one thing is sure: your body has all kinds of tricky ways to "burn" calories other than in the form of exercise. You can get *hot* from overeating, for example. When I eat more than I need I don't gain weight: I sweat in my sleep, I get fidgety, I have the urge to exercise. That's when I eat a *little* more than I need. If I were to engage in a conscious program of sustained overfeeding I'm sure I would gain weight.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 11:06 PM

@Travis, right, that would be another thing to work into one of the two boxes. (I would think you can either subtract it from calories in or add it to calories expended.)

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 09:45 PM

Well said Travis!

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 09:06 PM

P.S. Gary, One famous study showing considerably more weight loss on LC vs. LF was because the low carbers lost like 3kg lean mass to 1 kg for the low fat group. I plan to blog on that soon and will try to link to that here if I remember.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 09:04 PM

Hi Gary -- actually it does. Carbs are muscle sparing. Unfortunately most CRD's are too low in protein as they are constructed as a percent. Keep protein sufficient and there will be some lean mass lost (actually you want that with considerable fat loss anyway), but more will be spared.

Medium avatar

(39831)

on January 23, 2012
at 08:45 PM

Diet-induced thermogenesis has a significant impact on calories in.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 08:30 PM

@Nance: If you're eating whole foods vs. highly refined foods, this can make a difference in the number of calories you extract from your food.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 08:27 PM

Gary, Do you have any REAL evidence of this? Or just anecdotes? I've yet to see where LC/HF favorably impacts metabolism vs. LF/HC ... if anything the balance is tilted slightly in favor of the opposite.

Ccacf7567273244733bc991af4ac42ed

(5198)

on January 23, 2012
at 08:26 PM

I guess, but then he didn't include the energy of the air I breathe in...

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 07:37 PM

@Primal Danny, I thought miked included that in his "out" box (so to speak): "Going to the bathroom: The stuff that comes out contains some energy." I think he could actually put some of the stuff from the following paragraphs into the box also: the feedback loops, for example, although I'm guessing miked would consider those part of either "Base metabolic rate" or "exercise."

Ccacf7567273244733bc991af4ac42ed

(5198)

on January 23, 2012
at 07:29 PM

It's not that easy - I don't even digest all the calories I eat.

Ccacf7567273244733bc991af4ac42ed

(5198)

on January 23, 2012
at 07:27 PM

That's a problem with what you eat, not your metabolism. Not forgetting that 'normal' BMRs are measured from a SAD baseline.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 07:19 PM

And yes, it probably has something to do with leptin somehow or other, since leptin is a big player in the regulation of fat mass. See Stephan on this.

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on January 23, 2012
at 07:14 PM

IMO, enjoyment justifies any legal activity. :-))

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 05:58 PM

PrimalDanny - the reports I've read claim that there is a BMR reduction related to reduced weight (which I guess is OK and normal) and then on top there is a further reduction of 300-400 calories. So if a normal BMR is 2,000 cals for my height and weight, then if I got there from much heavier, my BMR might only be 1700 cals. It would therefore be more difficult to maintain my reduced weight if I return to my pre-diet eating level, and a normal maintenance diet of 2,000 cals...it would now be too much. This leads to yo-yo effect.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 05:50 PM

There seems to be a lot of merit to this approach -- both from a keep the body guessing point of view, and a sustainability one as well. I think a lot of people think "I'm going on a diet" so they can't have a whole slew of foods for months or it will sabotage them. If they realized, y'know fasting for one day is not the end of the world, or even a 500 cal/day day, or 3x 1000 cal/day or whatever so that it averages out to the usual cal/day will get you where you're going at least as fast.

Ccacf7567273244733bc991af4ac42ed

(5198)

on January 23, 2012
at 05:32 PM

What's wrong with a reduction in metabolism?

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 05:31 PM

Thanks Nance. Never would have guessed that one...

77877f762c40637911396daa19b53094

(78467)

on January 23, 2012
at 05:29 PM

Actually Evelyn, there is evidence that eating low carb, one can eat well past maintenance and NOT gain weight.

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on January 23, 2012
at 05:27 PM

The first time I saw SHAD it was used by FED; don't remember how he defined it but I call it supposedly healthy American diet (low-fat, complex carb, etc.)

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on January 23, 2012
at 05:17 PM

Dr Kruse could give a more learned answer but my guess is that the "slow metabolism" was probably a sign of leptin resistance. One reason I'm probably losing fat on much more food now is that I've clearly solved my LR problem based on about 6" of fat lost around my waist.

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 05:13 PM

Thanks Nance - is the "famine" response lowered leptin, then?

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 05:12 PM

Sorry being slow...I get SAD, but what is SHAD?

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on January 23, 2012
at 04:57 PM

I can't disprove your argument, Evelyn, but it really doesn't seem to match what I'm experiencing. I'm definitely "averaging" more food than I did before, particularly if you include my occasional splurges, yet I'm losing instead of plateauing or gaining as I did before. And I'm probably less active than I was before since I'm old now. :-))

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 04:48 PM

Thanks Evelyn...so why doesn't the exercise and higher protein preserve lean mass on a more "normal" (sorry, don't know exactly how to describe it...) higher carb, low fat diet (which I assume makes up the bulk of the diets that were measured to get the lower BMR result in the research)?

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8 Answers

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4
Medium avatar

on January 23, 2012
at 08:57 PM

There are two major things at play here with regard to a decrease in BMR. The first is simply that as one becomes less massive, the muscles (specifically in the legs, but also various postural ones) that were being recruited to move around that bulk atrophy because they are no longer subject to the same forces. This of course would be mitigated by someone who replaced those forces with ones in the gym. Lean body mass is the primary determinant of BMR. People fret about losing muscle when they lose fat, but the body requires a compelling argument in the form of forces on the muscle in order to maintain energetically costly muscle.

The second major thing affecting a reduction in BMR is what I like to call hypothalamic austerity measures. If your hypothalamus detects an energy shortage, it will react accordingly and decrease metabolic rate in order to conserve energy. There's also evidence that it actually makes muscles more efficient, though I don't know by what mechanism that occurs (possibly a reduction in the activity of uncoupling proteins, so less energy is lost as heat).

The perceived energy shortages can be further subdivided into acute shortages, like if you fast or restrict carbohydrates and more chronic shortages, like a perceived reduction in bodily energy stores (fat). I say perceived because it doesn't matter how much fat you actually have if there isn't enough leptin being produced and/or it isn't making its way to the arcuate nucleus of the hypothalamus and properly reflecting bodyfat stores.

People talk about "calories" all the time, but we are not in possession of a calorimeter. Glucose and fat availability are what is tracked. If the liver doesn't run out of glycogen and the hypothalamus doesn't "think" the body has run out of fat, then BMR doesn't drop below where it ought to be for a given individual's lean body mass.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 09:45 PM

Well said Travis!

Medium avatar

(39831)

on January 24, 2012
at 06:56 AM

Yeah, that's what I meant: those fibers are constantly being recruited to heft that weight around. An obese person's calves are a perfect example of this since they'll likely be used a lot even if the person is fairly sedentary. The more active they are, the more muscle. A very large person who isn't totally bed-ridden probably has more muscle in their legs than I do in my entire body.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 11:26 PM

Michael Eades makes a good point about muscle being metabolically expensive, namely that it isn't really. It's in this old post of his: http://www.proteinpower.com/drmike/low-carb-library/are-we-meat-eaters-or-vegetarians-part-ii/ He gets it, more or less, from the Aiello et al. article on the expensive tissue hypothesis. I haven't read a whole lot of work on this, and I don't really feel like hunting right now, but if you think about it, it makes sense. Brain, heart, kidney, liver, and GI tract use up the most. Some more from me here: http://paleohacks.com/questions/27036/

Medium avatar

(39831)

on January 24, 2012
at 12:38 AM

Anything beyond what's necessary for survival is expensive. The synthesis of muscle needs to be accounted for, not just the energetic needs of inert muscle.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 24, 2012
at 03:50 AM

Hmmm, good call. I wonder though if the energy needs for new muscle synthesis really compares much to the day-in-day-out needs of the brain, heart, kidney, liver, and GI tract. Another issue: perhaps carrying around a lot of extra fat on the body requires not just the **existence** of those muscles but also their constant **use**, so that's something to work into the comparison. Whereas in the Eades point he was only talking about the existence. Still I'd like to see more numbers. I'll file it away as a mental note. Let me know if you see anything too.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 24, 2012
at 12:27 PM

Sweet, sounds like a good way to build up my leg muscles.

Medium avatar

(10611)

on January 24, 2012
at 01:14 PM

Walk, Paul, walk. My BMR ran true to the correlations throughout my weight loss, and dropped about 500 cal/day for a loss of 50 pounds. Using my calves/thighs (and arms since I started using a walking stick) daily added back that much and more to my metabolism.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 24, 2012
at 09:39 PM

@thhq, you don't think massive weight gain is a good way to build up my leg muscles? This is controversial advice you're giving out here on PH.

4
47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 07:17 PM

Hi, Gary. First of all I would say go read my answer here. I also link to lots of other places on PH where this general topic is discussed, including a large thread in which I have another answer. I've thought about this a whole lot and think that I've come to some good ways of straightening out the concepts. Well, for me at least.

But I also see you are asking a more specific question, or a variant of the basic question. I think I can only respond briefly right now. Basically, I would say that if you have eaten paleo with lots of nourishing micronutrients and you've fixed up your hormones and your general health, then if your body mass changes and your basal metabolic rate changes then your appetite will change also.

Now that's if everything goes correctly. Goodness knows what other factors can come into play. But think of it this way: my six-year-old niece has a much smaller body mass than I do and a much lower basal metabolic rate. Weirdly neither I nor her parents are worried about restricting her diet in order to prevent her from rapidly "returning" to my body weight.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 07:19 PM

And yes, it probably has something to do with leptin somehow or other, since leptin is a big player in the regulation of fat mass. See Stephan on this.

3
24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 04:44 PM

There is none. If you lose weight on paleo or any other approach, you have reduced calories, if not intentionally restricted them. There is a lot of confusing nonsense out there about some metabolic advantage of eating low carb, or that low carb diets aren't reduced calorie diets.

The reduction in metabolism is seemingly inevitable if it's going to happen to you. However exercise and higher protein can help preserve lean mass.

Ccacf7567273244733bc991af4ac42ed

(5198)

on January 23, 2012
at 05:32 PM

What's wrong with a reduction in metabolism?

77877f762c40637911396daa19b53094

(78467)

on January 23, 2012
at 05:29 PM

Actually Evelyn, there is evidence that eating low carb, one can eat well past maintenance and NOT gain weight.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 08:30 PM

@Nance: If you're eating whole foods vs. highly refined foods, this can make a difference in the number of calories you extract from your food.

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 05:58 PM

PrimalDanny - the reports I've read claim that there is a BMR reduction related to reduced weight (which I guess is OK and normal) and then on top there is a further reduction of 300-400 calories. So if a normal BMR is 2,000 cals for my height and weight, then if I got there from much heavier, my BMR might only be 1700 cals. It would therefore be more difficult to maintain my reduced weight if I return to my pre-diet eating level, and a normal maintenance diet of 2,000 cals...it would now be too much. This leads to yo-yo effect.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 09:04 PM

Hi Gary -- actually it does. Carbs are muscle sparing. Unfortunately most CRD's are too low in protein as they are constructed as a percent. Keep protein sufficient and there will be some lean mass lost (actually you want that with considerable fat loss anyway), but more will be spared.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 09:06 PM

P.S. Gary, One famous study showing considerably more weight loss on LC vs. LF was because the low carbers lost like 3kg lean mass to 1 kg for the low fat group. I plan to blog on that soon and will try to link to that here if I remember.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 11:09 PM

Whether a high-fat or low-fat diet is better for someone trying to lose weight, one thing is sure: your body has all kinds of tricky ways to "burn" calories other than in the form of exercise. You can get *hot* from overeating, for example. When I eat more than I need I don't gain weight: I sweat in my sleep, I get fidgety, I have the urge to exercise. That's when I eat a *little* more than I need. If I were to engage in a conscious program of sustained overfeeding I'm sure I would gain weight.

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 04:48 PM

Thanks Evelyn...so why doesn't the exercise and higher protein preserve lean mass on a more "normal" (sorry, don't know exactly how to describe it...) higher carb, low fat diet (which I assume makes up the bulk of the diets that were measured to get the lower BMR result in the research)?

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on January 23, 2012
at 04:57 PM

I can't disprove your argument, Evelyn, but it really doesn't seem to match what I'm experiencing. I'm definitely "averaging" more food than I did before, particularly if you include my occasional splurges, yet I'm losing instead of plateauing or gaining as I did before. And I'm probably less active than I was before since I'm old now. :-))

Ccacf7567273244733bc991af4ac42ed

(5198)

on January 23, 2012
at 07:27 PM

That's a problem with what you eat, not your metabolism. Not forgetting that 'normal' BMRs are measured from a SAD baseline.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 08:27 PM

Gary, Do you have any REAL evidence of this? Or just anecdotes? I've yet to see where LC/HF favorably impacts metabolism vs. LF/HC ... if anything the balance is tilted slightly in favor of the opposite.

2
96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on January 23, 2012
at 04:43 PM

Hi, Gary! Others can cover the science but I have personal experience in this area. Namely, my metabolism definitely slowed down on some of my previous diets and I regained weight astonishingly fast.

I'm 9 months into ancestral eating and have used IF for at least 6 months of that time. I haven't noticed any slowing of my metabolism despite losing a lot of excess fat on this lifestyle, and I do have a working hypothesis. When I IF, I don't binge the next day but I certainly eat a robust menu. When I was counting calories, I would eat the same amount every day--1500 usually.

My hypothesis: consistent low calorie intake triggers the "famine" response and metabolism slows to keep you alive longer but IF involves "feast and famine" so the survival response is not triggered. I think it's all about eating very well on the days you eat--if you fail to replenish your reserves and take good care of your body it would be very easy to trigger the famine response. But as long as you eat well, skipping part or all of a day is fine.

24df4e0d0e7ce98963d4641fae1a60e5

on January 23, 2012
at 05:50 PM

There seems to be a lot of merit to this approach -- both from a keep the body guessing point of view, and a sustainability one as well. I think a lot of people think "I'm going on a diet" so they can't have a whole slew of foods for months or it will sabotage them. If they realized, y'know fasting for one day is not the end of the world, or even a 500 cal/day day, or 3x 1000 cal/day or whatever so that it averages out to the usual cal/day will get you where you're going at least as fast.

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on January 23, 2012
at 05:17 PM

Dr Kruse could give a more learned answer but my guess is that the "slow metabolism" was probably a sign of leptin resistance. One reason I'm probably losing fat on much more food now is that I've clearly solved my LR problem based on about 6" of fat lost around my waist.

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 05:13 PM

Thanks Nance - is the "famine" response lowered leptin, then?

792634a784ec6a636c3137d0903e11b4

(1196)

on January 25, 2012
at 12:38 AM

This is really interesting! Nance and Evelyn, you've both answered my question (unwritten, lol) about IF and metabolism. I'm a very hard loser in spite of being obese, and am trying IF as the next stage in my strategy. My sense so far (4 weeks in) is that I'm not triggering the exhaustion or starvation I've experienced using more regular daily caloric restriction. Good to hear that it's likely to be theoretically as well as empirically sound ;)

1
510bdda8988ed0d4b0ec0b738b4edb73

(20898)

on January 23, 2012
at 07:24 PM

Well, let's start with a true statement (and this really IS true)

Change in Weight = Calories in - Calories out

Well, to be technical, there are 3500 calories per pound, so you need to do that conversion, but this is true. However, it is not nearly as simple as everyone thinks, but of course you know that, since you're here on PH. Let's look at "Calories in". That's easy: you eat it, it's "calories in".

"Calories out" is much harder, here are some things that contribute to calories out:

Base metabolic rate: just what you're burning when you sit there

Exercise: anything you burn above when you're sitting there

Breathing, you breath out CO2, O2, H2O, Ketones, all of which contain energy

Going to the bathroom: The stuff that comes out contains some energy

So, if we go all "Biggest Loser" on you, and say eat less and exercise more, you'd naively think, well calories in is smaller and calories out is larger, so I'll lose weight. Then you get all crazy technical and say if I cut calories by 100 a day, that means I'll lose 1 pound a month and all that nonsense which we know is not true.

What happens is that you have (almost) complete control over "calories in" because it has to go down your pie hole, and you have some control over calories out because you can exercise more. But that's all you have control over. The rest is controlled by your body. It has tons of feedback loops that it's trying to work with, so if you start restricting calories in, your BMR will go down to match that (and you'll also become more efficient when exercising, so you won't burn as much doing the same thing). The only way to have any control over what happens inside (the partitioning of "calories out") is to get your signalling (hormones) set up right, and that's why "paleo" works. It fixes the signals, so that that feedback loops work right.

That didn't come out as clear as I had hoped, but I have to run to a meeting now and don't have time to make it better.

Ccacf7567273244733bc991af4ac42ed

(5198)

on January 23, 2012
at 07:29 PM

It's not that easy - I don't even digest all the calories I eat.

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 11:06 PM

@Travis, right, that would be another thing to work into one of the two boxes. (I would think you can either subtract it from calories in or add it to calories expended.)

543a65b3004bf5a51974fbdd60d666bb

(4493)

on January 24, 2012
at 04:15 AM

@PrimalDanny, re your comment "I don't even digest all the calories I eat". You may already be aware of this, but others may not; food calories are an estimate of the product's digestible constituents only. The calorie calculation attempts to take in to account the fact that not all food eaten is actually absorbed by the body. http://en.wikipedia.org/wiki/Food_energy#Nutrition_labels

47a42b6be94caf700fce9509e38bb6a4

(9647)

on January 23, 2012
at 07:37 PM

@Primal Danny, I thought miked included that in his "out" box (so to speak): "Going to the bathroom: The stuff that comes out contains some energy." I think he could actually put some of the stuff from the following paragraphs into the box also: the feedback loops, for example, although I'm guessing miked would consider those part of either "Base metabolic rate" or "exercise."

Ccacf7567273244733bc991af4ac42ed

(5198)

on January 23, 2012
at 08:26 PM

I guess, but then he didn't include the energy of the air I breathe in...

Medium avatar

(39831)

on January 23, 2012
at 08:45 PM

Diet-induced thermogenesis has a significant impact on calories in.

543a65b3004bf5a51974fbdd60d666bb

(4493)

on January 24, 2012
at 04:09 AM

@PrimalDanny, re your comment "I don't even digest all the calories I eat". You may already be aware of this, but others may not; food calories are an estimate of the product's digestible constituents. The calorie calculation attempts to take in to account the fact that not all food eaten is actually absorbed by the body. http://en.wikipedia.org/wiki/Food_energy#Nutrition_labels

1
21b36b3de8ff31b0d41e7f0f4b5c1e03

(1688)

on January 23, 2012
at 07:10 PM

My personal experience so far has been that the paleo diet decreases BMR quite significantly.

The link below is a week-by-week analysis of my experience with Paleo over a period of five months. Basically, weight is going up despite more energy expenditure and fewer calories consumed.Not sure what is cause and what is effect.

I am experimenting with eating 50% more carbs as of last week, but too early to tell at this point.

http://www.flickr.com/photos/209297[email protected]/6750377697/in/photostream

Obviously, this is just one person's experience.

And yes, I am probably a bit too scientific about measuring all this stuff, but I enjoy these little experiments.

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on January 23, 2012
at 07:14 PM

IMO, enjoyment justifies any legal activity. :-))

0
246ebf68e35743f62e5e187891b9cba0

(21420)

on January 23, 2012
at 04:48 PM

There is a lot of stuff going on.

Here's my SWAG on the subject...

On a standard high carb, low fat, SHAD weightloss diet - the insulin highs and lows will prompt the dieter to gorge often. If they can fight these impulses, they will successfully do the same thing with their BMR, although they probably won't be healthier from an autoimmune standpoint, as a result.

The insulin highs/lows from a Paleo weightloss diet is much less, so you basically only eat when hungry, not when you are tired, fatigued, etc... so the chance of gorging yourself is less likely. Also, due to the healing properties of eating a significantly less inflammatory diet results in more energy, ergo more calorie expenditure.

Medium avatar

(10611)

on January 24, 2012
at 04:36 PM

My point is more the use of deprecating monikers which reflect a "holier than thou" attitude. I see paleo as a loose practicum, not as a precisionist theology. Walking 10 miles a day, every day, is a more paleo way of living than eating grass fed beef and dietary supplements.

246ebf68e35743f62e5e187891b9cba0

(21420)

on January 24, 2012
at 01:44 PM

thhq - that's just "doing it right". No need for a label. I like the SHAD moniker to separate it from SAD - Seasonal Affective Disorder.

Medium avatar

(10611)

on January 24, 2012
at 01:08 PM

So then we have the PHAD (Paleo "Healthy" American Diet)too? Stereotypes begone!

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 05:12 PM

Sorry being slow...I get SAD, but what is SHAD?

6cdc6b1e75690cfcc4804a6c9eaa910a

(2171)

on January 23, 2012
at 05:31 PM

Thanks Nance. Never would have guessed that one...

96bf58d8c6bd492dc5b8ae46203fe247

(37227)

on January 23, 2012
at 05:27 PM

The first time I saw SHAD it was used by FED; don't remember how he defined it but I call it supposedly healthy American diet (low-fat, complex carb, etc.)

8eade6b270dc874843f74fa599fa8754

(163)

on January 24, 2012
at 02:47 AM

"Standard 'Healthy' American Diet"

Medium avatar

(10611)

on January 24, 2012
at 05:52 PM

And why should we be confined by a single nationality? Those from the UK subsisting on bangers, mash and spotted dick would know that their diet SUKD. And those in the paleo healthy mode would be PHUKD.

0
Ccacf7567273244733bc991af4ac42ed

on January 23, 2012
at 04:40 PM

I think it's all about the carts and the horses. If you 'diet' for a certain period of time by artificially restricting your calories but using standard foods, you'll end up malnourished, hungry, and possibly even more messed up hormonally than when you started. However if you change your food sources and lifestyle then the change in calorie intake happens as effect rather than cause. You're in a much healthier place, and you don't have a ravenous hunger to force you to stop dieting. It just gets easier and easier, because it's about finding the balance within your body. Once you're healthy, you can tolerate pretty large swings in intake and metabolism from hour to hour and day to day - so long as it eventually swings back again. The idea of a fixed static BMR is not terribly helpful.

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