Monday, July 16, 2012

The 14-percent advantage of eating little and then a lot: Is it real?

When you look at the literature on overfeeding, you see a number over and over again – 14 percent. That is approximately the increase in energy expenditure you get when you overfeed people; that is, when you feed people more calories that they need to maintain their current weight.

This phenomenon is related to another interesting one: the nonlinear increase in body weight and fat mass following overfeeding after a period starvation, illustrated by the top graph below from an article by Kevin Hall (). The data for the squares on the top graph is from the Minnesota Starvation Experiment (). The graph at the bottom is based mostly on the results of a simulation, and doesn’t clearly reflect the phenomenon.

Due to the significant amount of weight lost in what is called above the semistarvation stage (SS), the controlled refeeding period (CR) actually involved significant overfeeding. Nevertheless, weight was not gained right away, due to a sharp increase in energy expenditure. That is illustrated by the U-curve shape of the weight gain in response to overfeeding. Initially the gain is minimal, increasing over time, and continuing through the ad libitum refeeding stage (ALR).

Interestingly, overfeeding leads to increased energy expenditure almost immediately after it starts happening. It seems that even one single unusually big meal will significantly increase energy expenditure. Also, the 14 percent is usually associated with meals with a balanced amount of macronutrients. That percentage seems to go down if the balance is significantly shifted toward dietary fat (), probably because the metabolic “cost” of converting dietary fat into body fat is low. In other words, large meals with a lot of fat in them tend to cause a reduced increase in energy expenditure – less than 14 percent. Shifting the balance to protein appears to have the opposite effect, increasing energy expenditure even more, probably because protein is the jack-of-all-trades among macronutrients ().

The calorie surplus used in experiments where the 14 percent increase in energy expenditure is observed is normally around 1,000 calories, but the percentage seems to hold steady when people are overfed to different degrees () (). Let us assume that one is overfed 1,000 calories. What happens? About 140 calories are “lost” due to overfeeding.

What does this have to do with eating little, and then a lot, in an alternate way? It allows for some reasonable speculation, based on a simple pattern: when you alternate between underfeeding and overfeeding, you reduce food consumption for short period of time (usually less than 24 h), and then eat big, because you are hungry.

It is reasonable to assume, based on the empirical evidence on what happens during overfeeding, that the body reacts to “eating big” as it would to overfeeding, increasing energy expenditure by a certain amount. That increase leads to a reduction in the caloric value of the meals during overfeeding; a reduction of about 14 percent of the overfed amount.

But the body does not seem to significantly decrease energy expenditure if one reduces food consumption for a short period of time, such as 24 h. So you have the potential here for some steady fat loss without a reduction in caloric intake. Keeping a calorie intake up above a certain point is more important than many people think, because a calorie intake that is too low may lead to nutrient deficiencies (). This is possibly one of the reasons why carrying a bit of extra weight is associated with increased longevity in relatively sedentary populations ().

Is this 14-percent effect real, or just another mirage? If yes, what does it possibly translate into in terms of fat loss? More on these issues is coming in the next post.


js290 said...

Ned, it should be clear to anyone with some formal mathematics (and/or engineering) training that energy input and energy output are coupled; they can't be treated independently. So any model that tries to decouple these two variables is inherently wrong.

The other detail that people miss is when the body will use the energy we ingest. So, even if dietary fat doesn't necessarily provide the maximal increase in energy expenditure, what's important is the ability to ultimately tap the stored fat for energy. As Dr. Rosedale puts it, people don't get fat by eating it, they get fat by not being able to burn it.

igel said...

people on warrior / leangains protocols (myself included) can definitely say that it is NOT a mirage: fasting and then eating big is a cool way to burn fat and build muscle (if one intends to do so) simultaneously

Ned Kock said...

Hi js290. So, would you say that the effect is real, or a mirage? Also, the loss due to EE seems to be lower if the overfeeding is significantly shifted toward dietary fat.

js290 said...

Ned, I would say it's absolutely real. If we can believe that metabolism is slowed by reducing energy input, then it stands to reason that metabolism can be accelerated by increasing energy input.

Obviously the relationship is nonlinear; therefore I'm not surprised that dietary fat may have a different effect on energy expenditure.

Practically, it doesn't really matter the exact function. As long as the hormones and enzymes are biased towards burning more fat than they store, fat mass will be lost.

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Ned Kock said...

What I find interesting about this effect js290 is that the body does not seem to significantly decrease energy expenditure if one reduces food consumption for a short period of time, such as 24 h.

So you have potential here for fat loss if you alternate between lower and higher calorie intake, as long as you do that in short enough windows of time (less than 24 h).

This may be an explanation to the effect that igel mentioned in his comment, associated with some IF approaches.

David Isaak said...

Hi, Ned--

Have you seen this?

Of course, people are fond of noting that people aren't rats--and we really aren't fruit flies!

(And, of course, a calorie is no longer a calorie, either. Odd that Bray would be the one to prove it: )

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js290 said...

Ned, it is indeed interesting. I kind of also wonder whether the increase in energy expenditure associated with a "balanced diet" as opposed to a higher fat diet has more to do with the body trying to rid itself of excessive glucose. That is, while one's metabolism is functioning properly, the body will increase energy expenditure by burning off the glucose. But, if the metabolism is operating sub-optimally, the excessive glucose goes into storage. Whereas with with fat, the body is primed to use it for fuel at any time, so an increase in energy expenditure beyond that of a "balanced diet" is not as necessary. It'll increase some because there's more energy to be used, but the body isn't as "panicked" about it.

Also, I'm also a bit of an unqualified skeptic when people claim that low carb, per se, breaks their thyroid function, and is somehow restored by introducing dietary glucose. I have to wonder whether people with these experiences simply were not eating enough. And, the re-introduction of carbs simply meant a total increase in energy input. In other words, would they have experienced similar improvements in thyroid function by simply eating more?

CarbSane said...

Hi Ned, I have to look for it but I came across a study that demonstrated EE actually increases early in a fast. I tend to think if this is true, it goes away with habituation, so erratic IF may be better. That's just a hunch though.

Ned Kock said...

Hi David, thanks for the link. This reminds me of the earlier post on BMI and mortality:

Ned Kock said...

I think those are good points js290. There is one problem with a very high fat, low carb diet – neither liver nor muscle glycogen will be properly replenished. Depending on the amount of glycogen depleting exercise done, that type of diet may be unsustainable.

Ned Kock said...

Hi Evelyn. And I am not even considering that possible increase in EE during a fast (or period of calorie restriction), only the one resulting from overfeeding later on.

Jeffrey of Troy said...

This seems to me, as igel alluded to, to support IF + "overfeeding" when you do eat, just enough so that the daily avg over a week or so = what you would have gotten if you did neither. Same calories, different apportionment.

Specifically, eat big (esp pro) post-workout (recovery's where you make your gains). But if you ate that big all the time, you'd gain both muscle and fat, like many powerlifters.

David Isaak said...

>>Hi David, thanks for the link. This reminds me of the earlier post on BMI and mortality...

Yes, indeed, I thought of your post immediately.

js290 said...

Ned, that's why I go two weeks between glycogen depleting activity. ;-)

SEAJ said...

I am curious how the body knows its in a calorie surplus. I would speculate that its the abundance of specific nutrients.. maybe amino acids or glucose levels that cause the effect. Maybe supplementing whole foods with more rapidly digesting amino acids and or sugars at a caloric deficit could simulate the effect.

Ned Kock said...

Hi SEAJ. That is one of the crucial questions, which goes unanswered in the pubs that provide evidence for the 14-percent effect. Well, at least the ones I reviewed.

ProudDaddy said...

I remember the same study as CarbSane. If true, it eliminates one of the main common arguments against less than three meals a day.

My concern is that muscle protein synthesis might suffer with IF. Its refractory nature seems to be well established, and I can't find any good studies (DEXA, not BIA, etc.) that indicate body composition is not negatively impacted by IF. Can anyone assuage my fears?

ProudDaddy said...

I remember the same study as CarbSane. If true, it eliminates one of the main common arguments against less than three meals a day.

My concern is that muscle protein synthesis might suffer with IF. Its refractory nature seems to be well established, and I can't find any good studies (DEXA, not BIA, etc.) that indicate body composition is not negatively impacted by IF. Can anyone assuage my fears?

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Michael Holmes said...

Hi Ned,

I practice alternate day fasting. But I don't understand the role of IGF-1. Are high levels good or bad?
These studies by Fontana seem to suggest that IGF-1 should be kept low - and the easiest way is protein restriction.

Long-term low-protein, low-calorie diet and endurance exercise
modulate metabolic factors associated with cancer risk

Long-term effects of calorie or protein restriction on serum IGF-1 and IGFBP-3 concentration in humans

What do you think? Any ideas about how much or what kind of protein is optimal?

Thanks for the great work!