Wednesday, June 15, 2011

Effect of dietary fat on satiation within and between meals

Blundell et al performed a series of four experiments to determine the effect of fat content of a meal on satiety, both during and after meals. [1 full text ]

The first  experiment involved giving 16 lean, healthy subjects a standard breakfast of 440 kcal, or the same breakfast supplemented with either fat or carbohydrate calculated to provide ~360 kcal.  The standard breakfast consisted of orange juice, scones, and fruit yogurt.  The supplements consisted of either polyunsaturated margarine and cream, or a combination of sucrose, maltodextrin, and glucose.  The following table provides the data on the three types of breakfasts:


Each individual tested each breakfast with a one week interval between tests.  The subjects rated the palatability of the meals, and rated hunger, desire to eat, fullness, and prospective consumption before the breakfasts and periodically during the rest of the day.

After the breakfasts, the subjects ate measured meals, provided by the experimenters, for lunch and dinner on the same day, and kept weighed food records for the period between dinner that day and breakfast the next.

In this experiment, neither the high fat nor the high carbohydrate breakfasts appeared to exert any significant effect on intakes of macronutrients at the subsequent lunch or dinner.  However, subjective reports of hunger did differ between the high carbohydrate and high fat meals.   Specifically, the subjects reported less hunger with the carbohydrate-supplemented meal compared to the baseline or fat-supplemented breakfasts.  The following figure depicts the effects:



When the subjects ate the carbohydrate-enriched breakfast, they experienced less post-meal hunger than when given the fat-enriched breakfast, indicating that they found fat less satisfying than carbohydrate during the post-ingestive phase. 

In the second experiment, 12 lean healthy individuals consumed the same breakfasts given in experiment one, followed by a snack provided 90 minutes after the breakfasts.  Subjects rated themselves as less hungry and more full after the carbohydrate-enriched breakfasts, compared to the fat-enriched breakfasts.   They also ate smaller snacks at the 90 minute mark when they had the carbohydrate-enriched breakfast, compared to when they ate the fat-enriched breakfast.  The following figure depicts the effects:



In the third experiment, 16 lean healthy subjects consumed the same breakfasts as in experiment one, followed by a snack 90 minutes after the breakfast, or a meal 270 minutes after the breakfast.   The following table depicts the results:


When given the carbohydrate-enriched breakfast, the subjects  voluntarily ate a smaller snack at 90 minutes after, compared to what they ate after the fat-enriched breakfast.  Of interest, although the fat-enriched breakfast supplied ~800 kcal, 90 minutes after that breakfast they voluntarily consumed a snack the same size as they had 90 minutes after the 440 kcal baseline breakfast.  This means that at 90 minutes after the breakfast, the 800 kcal breakfast providing 57% energy from fat was no more satisfying than the 440 kcal breakfast providing only 10% energy from fat.  

The greater satiating effect of the high carbohydrate breakfast disappeared at 270 minutes.  Blundell et al attributed the greater satiating effect of the carbohydrate-supplemented breakfast at 90 minutes to the greater elevation of blood glucose achieved by the carbohydrate-rich breakfast.  As the glucose was oxidized or stored over the next 180 minutes, this satiating power declined.

In the fourth experiment, 12 obese women ate either one of two lunches, each on two different occasions.  One lunch supplied 527 kcal, the other supplied 985 kcal.  Between lunch and dinner, the subjects rated their hunger at one hour intervals.  At dinner, each woman was offered either foods supplying 50% of energy as fat, or 50% of energy as carbohydrate and allowed to eat as much as desired.  So, each woman had four different procedures:

1.  A 527 kcal lunch, followed by an ad libitum high-fat, low-carbohydrate (50% energy as fat) meal for dinner.
2.  A 527 kcal lunch, followed by an ad libitum low-fat, high-carbohydrate (50% energy as carbohydrate) meal for dinner.
3.  A 985 kcal lunch, followed by an ad libitum high-fat, low-carbohydrate (50% energy as fat) meal for dinner.
4. A 985 kcal lunch, followed by an ad libitum low-fat, high-carbohydrate (50% energy as carbohydrate) meal for dinner.

Not surprisingly, the size of the mid-day meal determined the course of subjective hunger during the afternoon, i.e. the smaller meal was followed by earlier return and greater intensity of hunger as depicted in the following figure:



However, the size of the midday meal did not affect the energy content of the ad libitum dinner meal as much as the relative fat and carbohydrate contents of the offered dinners.  The following table displays the impact of midday meal size and dinner composition on satiation during the dinner meal:

Regardless of whether given the high-energy or low-energy midday meal, the subjects consumed an average of 5.6 MJ/1336 kcal for dinner when given high-fat foods, but only 2.8MJ/677 kcal when given the high-carbohydrate/low-fat foods.  This demonstrated that within a meal, high-carbohydrate foods appear to have a greater satiating effect, i.e. subjects voluntarily consumed less food energy when given a high-carbohydrate selection compared to when given a high-fat selection.

Since the high-fat meal was at least 50% energy from fat, and the average intake was 1336 kcal, this means the average intake of non-fat nutrients at the high-fat meals was at most 668 kcal, approximately the same as the 677 kcal the women consumed when eating the low-fat high-carbohydrate meals. It appears as if the women were eating to achieve a certain intake of non-fat nutrients (carbohydrate or protein), regardless of the fat content of the food.  Since the high-carbohydrate meals supplied more carbohydrate and protein per ingested gram of food, the apparent carbohydrate or protein drive was satisfied with less total fat and energy intake.

The researchers followed the food intake of these women after dinner and throughout the next day as well.  Some would predict that the high fat intake of the high-fat meal would reduce post-meal and next-day food intake.  That did not happen.

 The women consumed after-dinner snacks averaging 310 kcal after the high-fat meal, and 391 kcal after the low-fat, high-carbohydrate meal.   The 81 kcal lower energy intake is insignificant compared to the nearly 700 kcal greater kcal intake at the preceding high- meal. 

The day after having the high-fat dinner, the women consumed an average of 1800 kcal, whereas the day after having the low-fat dinner, the women consumed an average of 1556 kcal.  This ~250 kcal difference did not reach statistical significance, but the direction was opposite of the prediction that they would compensate for the high-energy intake of the previous day by reducing energy intake in subsequent days.  It may even suggest that the high-carbohydrate dinner had a satiating effect that lasted into the next day. 

Now, looking at this from an evolutionary perspective:  If humans find carbohydrate more satisfying than fat, this suggests that evolutionary diets were high in carbohydrate and low in fat.  An organism geared to consuming fat would get the most satisfaction from fat.  An organism geared to consuming carbohydrate would continue eating until it either satisfied its carbohydrate requirement, or reached the limit of  its ability to convert protein or glycerol to carbohydrate, whichever comes first, regardless of “energy” intake--exactly as seen in these women. 

Since the brain regulates eating behavior and it primarily relies on glucose as its main fuel, we can reasonably expect that the brain has a carbohydrate drive, meaning that it drives people to eat until they ingest adequate glucose, or enough protein to provide the brain with adequate glucose.   

In other words, I would predict that, barring interference from the conscious mind (i.e. so-called "discipline") attempting to control macronutrient ingestion,  hungry people will keep eating until they at least minimally satisfy their carbohydrate requirements either directly from dietary carbohydrate, or indirectly from dietary protein, or until in the latter case they reach the limit the body imposes on protein ingestion, whichever comes first, regardless of total fat (or energy) intake.

Several studies appear to indicate that primitive Eskimo diets aligned with this prediction.  Several studies have indicated that Eskimos consume  very high percentage of energy as protein [Table from 2 full text ]:


On average these studies suggest that free living Eskimos derive 48% of energy from protein.  Assuming a 3000 kcal diet for an active male, this would be 1440 kcal/360 g of protein daily.  Since the human protein (70 kg reference man) requirement ranges from 50 to 75 g per day under most circumstances, these data indicate that the Eskimo may consume ~300 g excess protein daily.  According to Jungas et al, about 58% of catabolized protein will appear in the blood stream as glucose [3 ] .  Therefore, an Eskimo consuming about 300 g excess protein daily will generate from this about 174 g glucose, approximately the minimal amount required by the central nervous system. 

Some have criticized the data in the table above claiming that Eskimos eat ~80% of kcalories as fat based on claims made by Stefansson.  I find it extremely unlikely that four separate investigations produced incorrect data on Eskimo macronutrient consumption, and since Stefansson did not directly measure the macronutrient intake of Eskimos, I see no reason we should accept his estimate as more accurate.

The idea that Eskimos couldn’t have eaten a diet providing 48% of energy as protein is based on the claim that a protein intake of this magnitude will lead to so-called “rabbit starvation” from excess protein intake.  About “rabbit starvation” Cordain et al [4 ] have written:

“Excess consumption of dietary protein from the lean meats of wild animals leads to a condition referred to by early American explorers as “rabbit starvation,” which initially results in nausea, then diarrhea, and then death (39). Clinical documentation of this syndrome is virtually nonexistent, except for a single case study (42). Despite the paucity of clinical data, it is quite likely that the symptoms of rabbit starvation result primarily from the finite ability of the liver to up-regulate enzymes necessary for urea synthesis in the face of increasing dietary protein intake.” [Emphasis added]

Aside from the fact that clinical documentation of “rabbit starvation” is “virtually nonexistent,” Shaefer reported that primitive Eskimos on native diets had enlarged livers in comparison to Caucasians, and when they reduced protein intake, substituting carbohydrate, their livers reduced in size [5, full reference below].  This may suggest that Eskimos on native diets had livers adapted to chronically very high protein intakes via hypertrophy, whereas explorers (including Stefansson) may have experienced acute “rabbit starvation” when forced to eat very lean meat because unlike Eskimos they did not have previous lifelong exposure and hepatic adaptation to very high protein intakes.  

A Word About Protein And Satiety

A number of studies have shown that when given energy-restricted diets, people find higher protein intakes more satiating (within meals) and satisfying  (between meals) than lower protein diets.  For a while I felt impressed by this, thinking that protein is more satiating than any other nutrient. 

However, I now think this finding simply reflects the long-known fact that when when we restrict total food energy intake, and therefore carbohydrate intake, protein requirements increase, because carbohydrate restriction increases the use of lean mass to produce glucose.  Thus, under hypocaloric conditions, a drive to meet increased protein requirements--what we might call "protein hunger"-- may surface. 

Again, it has been known for a long time that protein requirements increase under hypocaloric conditions, so these recent studies showing higher protein diets to be more satiating under hypocaloric conditions appear to me to just be late application of something we have known for decades.  These findings do not mean that protein is the most satiating nutrient under all conditions.  I performed a quick PubMed search for studies of the satiating effects of protein under ad libitum conditions, and found only one study  [6 abstract ] which reported both "higher protein led to greater daily fullness" and "Protein quantity did not influence daily hunger, glucose, or insulin concentrations," i.e. inconsistent effects.


Given what we know about the satiating power of carbohydrate and protein, and fat balance versus energy balance, Astrup suggests that the optimal diet for reducing body fat might be very low in fat, high in carbohydrate, and moderately high in protein, for example 60-65/20-25/15 carbohydrate/protein/fat [7 abstract, 8 full text].

Take Home

1)  This series of clinical studies found that both lean and obese people not invested in consciously controlling their macronutrient intakes experienced most satisfaction and less hunger from high-carbohydrate than from high-fat meals.
2) The biological basis for this probably lies in the brain's demand for glucose.  The brain drives eating behavior, and since it prefers glucose to other fuels, it has a drive to satisfy its own requirement for glucose.
3)  Barring conscious control of macronutrient intake/ratios, a majority of people probably will eat to achieve an adequate intake of carbohydrate, either by consuming carbohydrate directly, or by consuming enough protein to produce adequate carbohydrate, continuing to eat until either they satisfy their carbohydrate drive, or they meet the limit of the body's ability to convert protein to carbohydrate, whichever comes first, and regardless of total energy intake. 
4) If people choose high-fat foods to satisfy carbohydrate requirements, they will very likely consume more fat (grams) than they can burn in a day, leading to progressive gain of fat weight.

Notes:

5. Schaefer O. Eskimos (Inuit). In: Burkitt DP, Trowell HC, eds. Western Diseases: Their Emergence and Prevention. Cambridge, MA:  Harvard University Press, 1981:114.

22 comments:

kyle said...

Don,

I think you write great articles and I am greatly intrigued by this new direction you are taking. Its just hard to fully accept it because you wrote such convincing arguments from both sides of the equation. I feel like I could accept a lower fat more carb approach as long as they are starcy tubers and not cereal grains. However, I am finding it hard to accept the downplay of protein and it sounds like your advocating less protein now. I think it would be great if you were to write about the importance of protein and how much is needed. I work out consistently and I strongly believe in the 1g of protein per pound of bodyweight. Is this not right?

psychic24 said...

Just a quick question. After reading numerous THINK for yourself blogs (i.e. healthyskeptic, archevore..etc), I seem to extract the idea that it is important to look over studies before making strong conclusions from them. I mean no offense by this, but the studies you are setting forth are so ridiculous that I just don't understand how you can possibly make the conclusion you are making. Everyone who advocated high fat diets does so under the premise that they lead to lower insulin levels which lead to less hunger through unrestricted access to your own fat cells. You on the other hand are comparing high fat and high carb diets that share the common baseline of "orange juice, scones, and fruit yogurt"?! that's already a high carb breakfast to begin with, so how can you possibly use these studies to create a dichotomy between high fat and high carb; THEYRE BOTH HIGH IN CARBS!!

Spencer King said...

Don,
You provided references for "the satiating effects of protein under ad libitum conditions" yet did not post any references that protein requirements are greater under hypocaloric conditions. I was unable to find any after a quick look on Google Scholar and Scrius, could you please post them if you have them handy?

Wouldn't an adaption period be required before fats and protein became more satiating? I'd also echo what Psychic24 said that both meals were quite high in carbohydrates, wouldn't this change the results?

Don said...

psychic,

You don't get it? The purpose of this study was to compare the satiating effect of fat to that of carbohydrate. Adding fat to the diet did not increase satiety, but adding carbs did. Thus, if in fact a low carb diet increases satiety (didn't for myself, my wife, or many others who have visited my blog) in some people, its not because it is high in fat. Further, this study showed that INCREASING carbs INCREASED satiety, exactly the opposite of the claim of low carb gurus. If they were correct, then this study should have shown that the people who ate the highest percentage of carbs had the lowest satiety. Basically, this study showed that the whole idea that carbs are 'not satisfying' because they increase insulin is BULLSHIT. In fact, some research indicates that one of the reasons they are satisfying is that they raise insulin levels, which the brain interprets as 'fed.' For example:

http://www.sciencedirect.com/science/article/pii/0031938494903107

"Thus, when insulin is increased during spontaneously taken meals, those meals are reduced in size and drugs which block insulin release, increase the size of meals; we assert insulin is a prandial satiety hormone which likely reduced feeding by increasing glucose uptake into peripheral tissue."

Most likely, the effect of insulin is bipolar, with too little secretion ( due to a diet too low in carbs) resulting in low satiety, and too much too fast (produced in response to refined carbs) also resulting in low satiety, but just the optimal amount (produced by eating whole foods) resulting in optimal satiety.

In any case, this study clearly showed that a diet high in refined carbs produced a greater satiety than one enriched with fat. The purpose was to find out why people so easily consume more fat than they need. The finding was that fat has a very weak effect on satiety relative to its "energy" content.

If low carb works for you just ignore this. But if it doesn't, it just might be that this study can explain why.

psychic24 said...

Either all the information that i've read on nutrition has been a great big misunderstanding, or something is not right here....

"Most likely, the effect of insulin is bipolar, with too little secretion ( due to a diet too low in carbs) resulting in low satiety, and too much too fast (produced in response to refined carbs) also resulting in low satiety, but just the optimal amount (produced by eating whole foods) resulting in optimal satiety."

Are you suggesting that potatoes (eaten without skin to avoid glycoalkaloids) and white rice have fundamentally different insulin responses? I mean one is a "whole food", while the other is refined; it just seemed to me their BS spikes were pretty similar, as well as the corresponding insulin response.

"Basically, this study showed that the whole idea that carbs are 'not satisfying' because they increase insulin is BULLSHIT'

I think you are being too critical here. Satiety is a rather general term in my opinion; you have supposedly "proved" that carbs satiate you more than fats, at least 90 mins after.... but 270 mins after where is the satiety? Personally i'd like to see what would happen in another 90 mins after that, but that's besides the point. Did you by any chance consider that maybe the insulin spike from all those carbs and tryptophan making its way through the BBB to be the cause of the acute satiety on these volunteers? makes sense why it wasn't sustained couple hours after...

"In any case, this study clearly showed that a diet high in refined carbs produced a greater satiety than one enriched with fat."

I disagree on how "clearly" this study showed anything at all. Last time i checked low carbers weren't referred to as high fatters, even though that is the tradeoff (gotta get your calories from somewhere). My point is that the reduction in carbs is the most important quality of this diet, it's not simply saying by adding fat you are increasing the satiety of your diet, but rather the lack of carbs allows that quality while supplying your body with calories from fat, which produces favorable metabolic conditions.
So saying that by adding fat or carbs to an already high carb meal and then concluding carbs are more satiating makes for a rather poor study. I just feel that after reading all the recent research on the blogosphere, or even after reading Good calories, Bad Calories(which is more a history book than anything, presenting the annals of refined carbs and their fattening effects), it makes no sense to argue in defense of refined carbohydrates.

p.s. the link you posted doesn't work.

EL 66K said...
This comment has been removed by the author.
EL 66K said...

Don, is there an study which shows that adding carbs to a low fat diet increases satiety? That would be better for your argument, specially in light of the theory of food reward.

Eric said...

How did you not stop reading the study here:

"The standard breakfast consisted of orange juice, scones, and fruit yogurt.  The supplements consisted of either polyunsaturated margarine and cream, or a combination of sucrose, maltodextrin, and glucose."

Scones, OJ, fruit, and yogurt were eaten in the high fat meal... with a side of trans fats.

Paleo Phil said...

EL 66K's question is a good one. The views of Stephan G., Lustig and others on food reward aka brain reward could explain how both you, Stephan, McDougall, Denise Minger, the traditional Kitavans, Gwi and others on the higher carb side and Gary Taubes, Kurt Harris, Mark Sisson, Michael and Mary Eades, the traditional Anbarra, Ache, Onge, Masai, Chukchi, Nenets, Evenks and others on the lower carb side appear to "succeed" (see http://perfecthealthdiet.com/?p=2168 for data on some of these). I'll define "success" as much lower levels of obesity and diseases of civilization than found in industrialized societies, plus both sides appear to think they have succeeded by their own definitions.

primalmami said...

I can't get past table 1 without asking how they authors could compare 3 different diets consisting of different total calorie counts and why the basic and high fat diets contained the same amount of carbs. Why weren't some of the carbs replaced by fat in the high fat diet instead?

Daddy said...

Okay, the confusion re your switch begins. After reading your post and the first comment, I chose to go and look at your past posts on protein. Here's what you said on January 4th of this year:

"You can’t draw conclusions about whole foods or diets based on whole foods from experiments done with isolated nutrients." I am no food expert but does supplementing with 'a combination of sucrose, maltodextrin, and glucose' fall under that same rule?

You also said, "Just to experiment, for a couple of days Tracy and I reduced our meat intake by half. I reduced my meat intake from more than a pound daily to just about one-half pound, and, as the Jaminets suggest, replaced the protein with starchy carbohydrates (potatoes and sweet potatoes). For both Tracy and I, this resulted in a noticeable decline in mood and a dramatic increase in hunger and intestinal gas, along with a disruption of bowel function." So higher carbs and lower fats lead to a dramatic increase in hunger?

You then go on to say, "One of the benefits I have received from paleo dieting has been a sharpening of my primal, unconscious guidance system. Basically, the longer I have eaten in a “primal” fashion, the less conscious effort I find myself putting into food selection. I follow my natural inclination to eat meat, fat, vegetables, fruits, and nuts in amounts determined by appetite rather than reason, and I get rewarded with pleasant moods, smooth digestion, abundant energy, and good health. Every time I interfere with this by trying to impose on my food selection some guidance from the haughty conscious mind, I have negative results, almost always appearing first in the digestive tract and mood.


The lesson I take from this is that the conscious mind does not know enough to regulate food intake, and, so long as I eat practically primal foods, I am better off if I leave regulation of food intake to primal wisdom of the body." But isn't this study heavily based on the subjects consciously choosing when and what to eat after the first meal given to them. You then base your evolutionary lesson-to-be-learned on those conscious decisions saying it must be the brain reacting based on its evolutionary programming. Is that also true when I eat a ton of sugar and then my mind tells me in an hour or two to eat more sugar? Is my brain then programmed through evolution to eat more and more sugar? And didn't you just say yesterday that the paleo/primal diet was essentially killing you and making you depressed? Only 5 months ago, it was making you feel at the top of the world.

I think I'm starting to understand the yin-yang theory on opposites - say one thing very adamantly and then say the opposite a short-time later.

It's almost as if you're trying to get a book deal.

Chuck said...

let's stop worrying so much about macronutrient ratios. there will be different ratios that work well for different people. also, these ideal ratios may fluctuate by day, by month, and by year for each person. just focus on eating nutrient dense, high quality, unprocessed foods.

Don said...

Kyle,

15-20% protein is not low in protein. 3000 kcal, 15% protein = 450 kcal as protein = 112.5 g protein; 20% protein = 600 kcal = 150 g. Brad Pilon did an excellent review of the research on protein requirements for muscle growth. Not one study showed a requirement greater than 120 g per day, and overall the studies indicate that 70-120 g of mixed proteins (plant and animal) will support maximum rates of muscle growth in typical individuals.

In one of his books, Ellington Darden PhD tells of his experience testing his own nitrogen balance when he was a PhD student at U Florida in nutrition and exercise science, and in hard training 3X weekly, and weighing ~200 lbs lean. Any time he went over ~75 g total protein daily (all sources) he spilled excess nitrogen in his urine. He didn't need more that 75g protein daily.

We're all worried about protein deficiency in America. When was the last time you heard of someone going to a physician and learning that he was suffering from kwashiorkor?

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002571/

At the top right of my page I have a link to purchase Pilon's review "How Much Protein?" I highly recommend it.

malpaz said...

yikes....hah sounds like "daddy" called you out rather well

Eric said...

Wow... This whole "revealing your new path" has resulted in a very interesting sociopsychological experiment! Looking at all the comments, you get the feeling many are insulted, disappointed or appalled by your recent musings and self-realizations! No need to take this stuff personal guys and gals! Thankfully, a few are grateful for Don sharing his knowledge and path. I happen to be one of those. Thank you for sharing Don and for reminding us all that no one really knows everything about everyone's unique physiological balance and requirements. Oh, and I will certainly check out Brad's "How Much Protein?" thingie...
Cheers :)

Don said...

Spencer,

I don't have an online reference handy but you can find it in any standard college nutrition textbook. For example pare 192 of Whitney and Rolfes Understanding Nutrition:

"..low energy intake will force the body to use the [dietary] protein to meet energy needs rather than to replace lost body protein."

page 182:

"Cells are forced to use amino acids for glucose and energy when glucose or fatty acids are limited...An adequate intake of carbohydrates and fats spares amino acids from being used for energy and allows them to perform their unique roles."

In hypocaloric conditions the body uses protein to produce glucose; this results in inadequate protein for maintenance of tissues. This would drive a hunger for protein; so a higher protein intake while hypocaloric would feel more satisfying than a lower intake. Studies also tend to show less lean mass loss during caloric restriction if diet is higher in protein...demonstrating that the higher protein intake better fits requirements under hypocaloric conditions. For example:

Layman DK, Evans E, Baum JI, et al. Dietary Protein and Exercise Have Additive Effects on Body Composition during Weight Loss in Adult Women. J. Nutr. 135: 1903–1910, 2005.

Thomas L. Halton and Frank B. Hu, MD, PhD The Effects of High Protein Diets on Thermogenesis, Satiety and Weight Loss: A Critical Review Journal of the American College of Nutrition, Vol. 23, No. 5, 373-385 (2004).

Brandon Berg said...

On the other hand:
http://www.ncbi.nlm.nih.gov/pubmed/18175736

And long-term studies have shown comparable weight loss for both low-fat and low-carbohydrate diets.

And then there's the study Stephan described here:
http://wholehealthsource.blogspot.com/search/label/Food%20reward

These aren't consistent with your glucose requirement hypothesis. Besides, glucose requirements can be met with a fairly moderate carbohydrate intake, not more than 150g or so, and through ketosis can be reduced to the point where they can be obtained through the conversion of glycerol and a very modest amount of protein.

Stephan's food-reward hypothesis resolves this apparent paradox: Reward value is highest for foods containing significant amounts of both fat and carbohydrate. Adding fat to a lowfat meal will increase its reward value and stimulate appetite, as will adding carbohydrates to a low-carbohydrate meal. But a meal low in either fat or carbohydrate will have low reward value, suppressing appetite.

In other words, I would predict that, barring interference from the conscious mind (i.e. so-called "discipline") attempting to control macronutrient ingestion, hungry people will keep eating until they at least minimally satisfy their carbohydrate requirements either directly from dietary carbohydrate, or indirectly from dietary protein, or until in the latter case they reach the limit the body imposes on protein ingestion, whichever comes first, regardless of total fat (or energy) intake.

This proves too much. If this were true, low-carbohydrate diets would make us ravenously hungry and lead to rapid and immediate fat gain, rather than rapid and immediate fat loss followed by, at worst, a slow and protracted regaining of the weight.

This idea may have some merit in the context of a single meal. That is, a person accustomed to deriving most of his energy from carbohydrate may not be sated by an unwonted low-carbohydrate meal because his brain is crying out for more glucose. But the brain will adapt within a few days to any level of dietary carbohydrate intake.

Alan said...

quick first reactions based on skimming through the article:

1. On the one hand, we must give the highest respect & regard to changes-of-heart based on an attempted rational re-thinking process.

2. Still on the first hand, we cannot strongly criticize the use of "tried it and it works gfreat for me" inductive-logic arguments, since we all do it to some extent; and other forms of process are exceptionally difficult to get at. LEx Rooker's series of actual sel-measurements of blood-glucose (before he settled on his current diet) are an exceptgionally unusual kind of experiment.

3. The other hand is this: it is not at all difficult to find the above two processes being used to come to RADICALLY different conclusions than Don did. The Vegan blogosphere and the pure-meat blogosphere are truly filled with examples.

Paleo Phil said...

Eric said...
"Thankfully, a few are grateful for Don sharing his knowledge and path."

I'm another one who's grateful, despite faring best on a VLC diet. I've learned quite a bit from folks who eat very differently from me, including even raw vegans, and I've never understood why I should get upset because someone fares well on a diet different than mine.

Brandon Berg said...

"Stephan's food-reward hypothesis resolves this apparent paradox: Reward value is highest for foods containing significant amounts of both fat and carbohydrate."

Yes, avoiding excessive food reward plus eating whole foods that aren't industrially processed (and the two are intertwined) and eating at least some nutrient-dense foods seem to be common factors among many of the success stories in both the low-carb and high-carb camps.

Sonnenschein said...

I am relatively new to your blog and have just witnessed the change your nutrition philosophy went through. I think to abandon a path that does not lead you to where you wish to be is courageous. I am abondoning my initial idea of Paleo/Primal - low carb, high fat, moderate protein but still stick to Paleo food as such. I started Paleo à la Mark Sisson about 6 months ago. I was at my ideal weight then and just wnated to improve my health. I gained 6 pounds and no, it wasn`t muscle from some magical recompositioning process in my body... I did NOT increase total calorie consumption and I was not very high carb before. I think in some person, esepcially females, high fat-low carb brings about metabolic disadvantages. I have increased my carb consumtion to 150 g/day two weeks ago while keeping protein moderate and fat moderate as well (macro-nutrient ratio varies widely) and I am shedding the pounds I have gained- again, calories staying the same. I have stopped keeping the carbs low at all costs and it seems to be just what my body needs. I am still avoiding grains but I am pretty sure the an accosional buckwheat pankace will not kill me...

Sanjeev said...

Looks like this study is providing data points along various parts of the graph, definitely not the entire graph.

It's not filling in the very low carbohydrate portion, so without other studies to look at, from this study alone that part of the curve is an extrapolation.

It's too bad that almost all the reports of "fat satisfies hugely and carb induces hunger" are anecdotal

This study does make complete sense though, for example, by reference to James Krieger's Insulin myths series.

Stan (Heretic) said...

That study seems to be completely contradicted by this. How would you explain the discrepancy?