Monday, April 4, 2011

The China Study II: Carbohydrates, fat, calories, insulin, and obesity

The “great blogosphere debate” rages on regarding the effects of carbohydrates and insulin on health. A lot of action has been happening recently on Peter’s blog, with knowledgeable folks chiming in, such as Peter himself, Dr. Harris, Dr. B.G. (my sista from anotha mista), John, Nigel, CarbSane, Gunther G., Ed, and many others.

I like to see open debate among people who hold different views consistently, are willing to back them up with at least some evidence, and keep on challenging each other’s views. It is very unlikely that any one person holds the whole truth regarding health matters. Unfortunately this type of debate also confuses a lot of people, particularly those blog lurkers who want to get all of their health information from one single source.

Part of that “great blogosphere debate” debate hinges on the effect of low or high carbohydrate dieting on total calorie consumption. Well, let us see what the China Study II data can tell us about that, and about a few other things.

WarpPLS was used to do the analyses below. For other China Study analyses, many using WarpPLS as well as HealthCorrelator for Excel, click here. For the dataset used here, visit the HealthCorrelator for Excel site and check under the sample datasets area.

The two graphs below show the relationships between various foods, carbohydrates as a percentage of total calories, and total calorie consumption. A basic linear analysis was employed here. As carbohydrates as a percentage of total calories go up, the diet generally becomes a high carbohydrate diet. As it goes down, we see a move to the low carbohydrate end of the scale.

The left parts of the two graphs above are very similar. They tell us that wheat flour consumption is very strongly and negatively associated with rice consumption; i.e., wheat flour displaces rice. They tell us that fruit consumption is positively associated with rice consumption. They also tell us that high wheat flour consumption is strongly and positively associated with being on a high carbohydrate diet.

Neither rice nor fruit consumption has a statistically significant influence on whether the diet is high or low in carbohydrates, with rice having some effect and fruit practically none. But wheat flour consumption does. Increases in wheat flour consumption lead to a clear move toward the high carbohydrate diet end of the scale.

People may find the above results odd, but they should realize that white glutinous rice is only 20 percent carbohydrate, whereas wheat flour products are usually 50 percent carbohydrate or more. Someone consuming 400 g of white rice per day, and no other carbohydrates, will be consuming only 80 g of carbohydrates per day. Someone consuming 400 g of wheat flour products will be consuming 200 g of carbohydrates per day or more.

Fruits generally have much less carbohydrate than white rice, even very sweet fruits. For example, an apple is about 12 percent carbohydrate.

There is a measure that reflects the above differences somewhat. That measure is the glycemic load of a food; not to be confused with the glycemic index.

The right parts of the graphs above tell us something else. They tell us that the percentage of carbohydrates in one’s diet is strongly associated with total calorie consumption, and that this is not the case with percentage of fat in one’s diet.

Given the above, one may be interested in looking at the contribution of individual foods to total calorie consumption. The graph below focuses on that. The results take nonlinearity into consideration; they were generated using the Warp3 algorithm option of WarpPLS.

As you can see, wheat flour consumption is more strongly associated with total calories than rice; both associations being positive. Animal food consumption is negatively associated, somewhat weakly but statistically significantly, with total calories. Let me repeat for emphasis: negatively associated. This means that, as animal food consumption goes up, total calories consumed go down.

These results may seem paradoxical, but keep in mind that animal foods displace wheat flour in this dataset. Note that I am not saying that wheat flour consumption is a confounder; it is controlled for in the model above.

What does this all mean?

Increases in both wheat flour and rice consumption lead to increases in total caloric intake in this dataset. Wheat has a stronger effect. One plausible mechanism for this is abnormally high blood glucose elevations promoting abnormally high insulin responses. Refined carbohydrate-rich foods are particularly good at raising blood glucose fast and keeping it elevated, because they usually contain a lot of easily digestible carbohydrates. The amounts here are significantly higher than anything our body is “designed” to handle.

In normoglycemic folks, that could lead to a “lite” version of reactive hypoglycemia, leading to hunger again after a few hours following food consumption. Insulin drives calories, as fat, into adipocytes. It also keeps those calories there. If insulin is abnormally elevated for longer than it should be, one becomes hungry while storing fat; the fat that should have been released to meet the energy needs of the body. Over time, more calories are consumed; and they add up.

The above interpretation is consistent with the result that the percentage of fat in one’s diet has a statistically non-significant effect on total calorie consumption. That association, although non-significant, is negative. Again, this looks paradoxical, but in this sample animal fat displaces wheat flour.

Moreover, fat leads to no insulin response. If it comes from animals foods, fat is satiating not only because so much in our body is made of fat and/or requires fat to run properly; but also because animal fat contains micronutrients, and helps with the absorption of those micronutrients.

Fats from oils, even the healthy ones like coconut oil, just do not have the latter properties to the same extent as unprocessed fats from animal foods. Think slow-cooking meat with some water, making it release its fat, and then consuming all that fat as a sauce together with the meat.

In the absence of industrialized foods, typically we feel hungry for those foods that contain nutrients that our body needs at a particular point in time. This is a subconscious mechanism, which I believe relies in part on past experience; the reason why we have “acquired tastes”.

Incidentally, fructose leads to no insulin response either. Fructose is naturally found mostly in fruits, in relatively small amounts when compared with industrial foods rich in refined sugars.

And no, the pancreas does not get “tired” from secreting insulin.

The more refined a carbohydrate-rich food is, the more carbohydrates it tends to pack per unit of weight. Carbohydrates also contribute calories; about 4 calories per g. Thus more carbohydrates should translate into more calories.

If someone consumes 50 g of carbohydrates per day in excess of caloric needs, that will translate into about 22.2 g of body fat being stored. Over a month, that will be approximately 666.7 g. Over a year, that will be 8 kg, or 17.6 lbs. Over 5 years, that will be 40 kg, or 88 lbs. This is only from carbohydrates; it does not consider other macronutrients.

There is no need to resort to the “tired pancreas” theory of late-onset insulin resistance to explain obesity in this context. Insulin resistance is, more often than not, a direct result of obesity. Type 2 diabetes is by far the most common type of diabetes; and most type 2 diabetics become obese or overweight before they become diabetic. There is clearly a genetic effect here as well, which seems to moderate the relationship between body fat gain and liver as well as pancreas dysfunction.

It is not that hard to become obese consuming refined carbohydrate-rich foods. It seems to be much harder to become obese consuming animal foods, or fruits.


Brian said...

I agree with your statements and it's great to see some vigorous and objective analysis applied to actual data - objective being key.

For the r-squared values, should they be interpreted as coming from a linear regression analysis? The order and strength of these variables makes sense (especially the negative association of animal foods), but if you interpret the coefficients similarly to regression analysis, the model is still accounting for less than 50% of total caloric consumption.

Am I interpreting your results correctly? If so, what about the other 58% of caloric intake?


Beth@WeightMaven said...

This is really fascinating!

One thought re IR. On his blog, Nigel Kinbrun says something to the effect that "a full cell is an IR cell" ... I like that, but wonder if it's that simple. There are clearly differences between someone who becomes diabetic at a BMI of 35 or 40 and someone who isn't at a BMI of 50 or 60 or more.

Also, I'm somewhat enamored with Peter@Hyperlipid's theory of hepatic injury and IR ( I need to catch up on your blog to see if you've addressed this in the past. Seems plausible that excess PUFA and fructose in our Western diet should be showing up in this equation as well.

John said...

Very informative post Ned.

Wheat displacing other carbs, wheat displacing animal fat, and wheat being the strongest contributor to total calories. That sounds awfully similar to the conventional wisdom advice about what is a 'healthy' diet... So there also is the possibility that the correlations are just the result of China following western dietary guidelines. SAD but (perhaps) true.

"If it comes from animals foods, fat is satiating [...] also because animal fat contains micronutrients [...]"

My guess: unprocessed animal fat is mainly satiating because it usually comes together with protein. As you said: "consuming all that fat as a sauce together with the meat". The protein stimulates an insulin + glucagon response. The glucagon will keep the blood sugar level steady, i.e., no glucose dip to cause hunger. The insulin will offload the fat and certain amino acids, and simultaneously it will act as 'postprandial leptin', i.e., reducing appetite by stimulating the release of alpha-MSH (anorexigenic) and inhibiting the release of NPY (orexigenic) in the hypothalamus.
And after insulin has done its job, it goes down and leptin gets back in charge to signal the energy reserve to the brain.


O Primitivo said...

I think these studies discussing the energy density and cost of foods may support you findings:

Nigel Kinbrum said...

@Beth: It could be that some people are better at creating new fat cells than others. Increasing fat cell hyperplasia reduces fat cell hypertrophy for a given fat mass.

The Thiazoladinedione (****glitazone) drugs for type 2 diabetes increase fat cell hyperplasia (at the expense of bone cells, unfortunately).

justdoinglife said...

Thank you for your post, more real information. This is one more example of nutrition displacement by wheat. Wheat cause me to be more hungry that without it. Your post show exactly what I would expect to happen when wheat diet is compared to rice diet.

@ Beth note:

A full cell is an IR cell, ok, and most muscle cells are full when a person in a gaining mode (overeating) regardless of there BMI. The issue is what type of fat is being stored, visceral, subcutaneous, intracellular, or elsewhere.
In feast mode, one is able to overeat because the excessive insulin has interfered with leptin signaling and failure to cancel of hedonic responses (Dr Lustig). The body is saturated with glucose and glycogen; that is one of the usual suspects for IR, independent of BMI. But we can grow more fat cells, or store it as visceral fat which has large cells, (sort of )and is first to take up excess fat (K. Hall et al). It is natural to be able to eat when food is available. Many of us need to learn to overcome our human nature and not eat when food is presented, or stop just as soon as we can.

It is suggested in several places that T2 occurs when the fat cells become IR or the muscle cells are unable restart glucose uptake thought the insulin pathway because cell membrane omega 6 damage.

To loose weight, I must decrease carbs to deplete glycogen, to force my body to burn fat (start glycogen sparing). Insulin and IR just follows along, responding to glucose load. Try to deplete glycogen when you are eating carbs; at best it is short bits of time.

My credentials are elsewhere. I just read and repeat stuff.

Ned Kock said...

Hi Brian. The R-squared values would go up if I added variables pointing at the variables to which they refer, even if the respective links were not associated with significant beta coefficients. An R-squared over 50 percent, for this type of study, is probably at the high end of the scale.

For conclusions regarding relationships between pairs of variables, the R-squared values are not very important. They are more useful as measures of overall explanatory power, especially in the context of multiple regression models like the one on the second figure.

Ned Kock said...

Hi Beth. Indeed, and contrary to popular belief, adipocytes (body fat cells) become increasingly insulin resistant as they increase in size and store more fat. That is where hyperplasia comes in.

The situation is a bit different with liver cells. Something needs to “damage” them to make the liver insulin resistant.

Ned Kock said...

Thanks for the links Ricardo.

Ned Kock said...

IR per se is not necessarily good or bad. It is absolutely necessary in some circumstances, which characterize physiological IR.

I don’t think physiological IR occurs in the context of intense exercise though, at least not if one has stored muscle glycogen. During intense exercise (e.g., weight training, sprints), muscle will consume sugar and fat; primarily sugar. But most of it will be derived from muscle glycogen.

Generally speaking, one would like body fat cells to be somewhat insulin resistant, and liver cells to be insulin sensitive.

Brian said...

Thanks for that clarification.

In your last comment, you said:

"Generally speaking, one would like body fat cells to be somewhat insulin resistant, and liver cells to be insulin sensitive."

This would be an ideal situation but the eat less and exercise more (e.g., walking) causes the opposite to happen because this does nothing to the glycogen stores - in the liver or muscle tissue. I think you wrote a post about this in the last year or so, correct?


john said...

Ned your last thought should have been the lead premise.....the epigenetic is effect is the key fact for the debate between carbs fat and protein. I did enjoy the post because it is step to furthering the truth that is unfolding daily on bench tops. Dr. K

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Anonymous said...

So the carbs in rice does not affect weight gain significantly... yet the last sentence in the conclusion doesn't mention rice... why?

What are your thoughts on black rice?

Peter said...

I'm mixed up about the carbs in rice. You said white glutinous rice is only 20% carbs, but when I looked it up it said 87%.

Jack C said...

Very interesting post Ned,

Regarding the satiating effect of fat:Fat, in a dose dependent manner, causes the transit time in the small intestine to slow by action of the ileal and jenjunal brakes. Intestinal transit time is effected more potently by fat content at the ileum at the end of the small intestine than by the content at the jejunum which is in the proximal half of the small intestine.

Activation of the ileal and jejunal brakes reduces food intake and increases satiety. Fat is the most potent trigger of the ileal brake. The type of fat seems to make no difference in activation of the ileal brake.

The cause of the observed spontaneous reduction in food intake in a high fat diet compared to a high carbohydrate diet seems to be well established.

Ned Kock said...

Hi Brian. Yes, if you check the labels at the bottom-right area of the blog, you’ll see that there are 8 posts on glycogen depletion.

Now, keep in mind that liver glycogen depletion happens all the time and we can greatly benefit from its effects. LC and IF are particularly good at depleting liver glycogen. Insulin levels tend to go down.

Muscle glycogen depletion is another story. It happens with endurance exercise, but you need a lot of it, and the depletion tends to be very localized.

Ned Kock said...

Hi Anon. The more unprocessed the grain, the more likely it is to retain its natural toxins. Having said that, I don’t eat rice at all. I do eat starchy natural foods like sweet and white potatoes, as well as yam.

Ned Kock said...

Hi Peter. This is from

Rice, white, glutinous, cooked (100 g)

Total Carbohydrate - 21.1g

Dietary Fiber - 1.0g

Sugars - 0.1g

Ned Kock said...

John and Jack C.: thanks.

Ned Kock said...

Btw, white glutinous rice is almost 80 percent water.

thhq said...

Like Peter I am also baffled by your 20% carb content for glutinous rice - I calculate 88%. Going a step further, wheat has more protein than rice, and I calculate 80% carb calories for white enriched flour.

Have you considered how economics affect calorie consumption? A plate of pork spareribs represents less calories for the money than a plate of wheat noodles. Satiation is not the only factor in play here.

Jack C said...

What happened

ben said...

Conventional wisdom says refined flour is much worse than whole (unprocessed) grains. Is that true?

Because there seems to be at least some data that show phytochemical (Phytates/phytic acid) and proteins (gluten) are not that bad.. and are perhaps even healthy! So before you soak the grains/legumes and discard the water.. check out the references in this post:

Steve Parker, M.D. said...

Ever eaten tabbouleh? It's usually made with a cracked wheat called bulgur, which you cook with hot water.


Bulgur, cooked, 100g:

19 g of carb
5 grams of fiber
Digestible carbs, then are 14 g

See Ned's numbers for rice above.

Peter said...

If cooking rice with water makes it low carb, why not have a glass of water with bread and make that low carb?

On the other hand, it does seem as if the rice- eating cultures have less heart disease, maybe they eat less stuff made out of sugar, wheat, and vegetable oil, I don't know why.

thhq said...

On the face of it I thought that Ned was making a comparison between wheat and rice as grains, and based on nutitionals I give wheat the edge because of the protein.

But after thinking about it further, I believe that Ned is comparing rice grain to wheat products. Not simple high carb matzos or bulgur, but the sinister fat/carb calorie-dense vehicles of obesity. They don't call it devil's food cake for nothing. And if the cake were made gluten-free using rice flour and lard instead of wheat flour and olive oil the results would be the same.

Incidentally the gluten-free version is quite tasty. Pastries have better texture when the protein is gone.

Ned Kock said...

Hi Ben. Traditional methods, such as soaking, seem to help reduce toxin content.

Much of the data I’ve seen suggests that refined wheat flour is akin to a modern plague. A related problem is that it is everywhere.

And, indeed, there is some evidence that some of the plant toxins may actually be helpful, but I think the reason is not well understood and that hormesis is claimed more often than it should be.

For example, it is possible that certain plant toxins are more toxic to harmful gut bacteria than to us, leading to an overall positive effect.

Ned Kock said...

Hi Steve. I ate what looked like tabbouleh on a visit to the Middle East a few years ago. Tasted pretty good!

I haven’t met many obese people in my trip, even though bread was widely consumed. That was a different type of bread than I’m used to seeing here, but was bread nevertheless.

I was told that one of the reasons for the leanness was the widespread consumption of khat, which was clearly visible on the streets. Khat is potent a stimulant and appetite suppressor.

Ned Kock said...

Hi Peter and thhq. I see your point Peter, but as thhq noted I referred to the carbohydrate content of white rice to try to explain the results.

Now, Peter, it is possible that the problem is with gluten, or with another component of refined wheat that we don’t even know about yet.

It is possible, for example, that increased wheat consumption leads to gut integrity problems, poor absorption of nutrients, and thus consumption of more calories. The “celiac route”, if you will.

The problem with this theory is that increased wheat consumption is also associated in this dataset with increased BMI. This points to the possible role of carbohydrates and insulin, discussed at the end of the post, as a more plausible explanation.

Peter said...

According to a USDA article about what Americans ate from 1909 to 2000, the amount of cabohydrates didn't change much in that time period, and was actually slightly lower in 2000 than 1909. Sugars and vegetable oil went way up, though.

I've traveled a lot in the developing world (not to China, though) and it seems like you find wheat much more in the form of pastries than as bread, so I wonder how much of the problems we attribute to wheat is attributable to the sugar and vegetable oil that you find with it.

thhq said...

Peter I attribute the obesity problem to the devilish and tasty combination of carbs and fat. Look at a fruit pie for instance, where the calories reside mainly in the crust. The innocuous fellow traveler.....

What are the fat/carb equivalents in China? I'll speculate that they have not switched to eating little debbies, but instead have been getting theirs in the form of potstickers, buns, fried noodles and the like. Western society doesn't have a patent on unhealthy foods. Greater affluence in China would lead to the same Western problems with inertia and overeating.

thhq said...

Peter I attribute the obesity problem to the devilish and tasty combination of carbs and fat. Look at a fruit pie for instance, where the calories reside mainly in the crust. The innocuous fellow traveler.....

What are the fat/carb equivalents in China? I'll speculate that they have not switched to eating little debbies, but instead have been getting theirs in the form of potstickers, buns, fried noodles and the like. Western society doesn't have a patent on unhealthy foods. Greater affluence in China would lead to the same Western problems with inertia and overeating.

Shel said...

hey Ned. man, this is good stuff. i haven't read the comments, so hope i'm not being redundant. in all the hoopla around the blogzoo, you have a decidedly pro-fruit bias that i find refreshing. i wonder if you could get into it a little more here and there.

i'm interested because in all my reading i have never found any real evidence, let alone proof that, in a paleoesque context (no free sugars, no refined starch, no grass seeds etc. (y'know, the usual dogma)), even an immoderate amount of fruit is implicated in visceral fat, obesity, vldl, diabetes, endogenous AGES leading to inflamation and other dietary demons.

i'm a paleo guy myself, but the theory of autumn fruit binging/fat storage for winter doesn't seem to coincide with fact. i simply can't find studies, outside of crappy diet paradigms, that implicate fruit in anything negative.

it would be nice for somebody to kick against the pricks regarding this.

Jack C said...


My "what happened" post a couple of days ago was an accident following my confusion after I lost a comment I was trying to post. I will remove it when I figure out how to do so.

Jack C said...


My earlier comment on the effect a low carbohydrate diet on the reducing of appetite and food intake was incomplete.

Clinical studies have shown that when undigested food reaches the ileum at the end of the small intestine, the speed of transit of food through the intestine slows down. Fat is the most potent trigger of the "ileal brake" simply because digestion of fat takes longer than carbohydrates or proteins.

Intestinal transit inhibition results in increased absorption of nutrients. In a healthy gut about 93% of fat consumed is consistently absorbed regardless of fat intake.

The decrease in gut motility due to the "ileal brake" is accompanied by an increase sense of fullness and reduced appetite that results in reduced caloric intake. Hence a high fat diet results in weight loss.

The effect of fat on reducing appetite and food intake is apparently mediated, at least in part, by cholecystokinin (CCK) an appetite suppressing factor synthesized in the gut in response to increased fat. In the following study, as little as three grams of fat perfused into the ileum increased CCK secretion in a dose dependent manner thereby increasing satiety resulting in reduced food intake.

Aging is associated with reduced appetite apparently as a result of increased sensitivity to CCK as well as increased synthesis of CCK with age. The resulting reduction in food intake often results in excessive, unhealthy weight loss. (PMID 20590826)

While the problem of excessive weight loss in the elderly is common, by and large those in conventional medical practice are often at a complete loss as to what to do about it. The most common solutions offered are (1) You are depressed: take anti-depressants. (wrong) (2) You simply need to eat more: That is impossible if your gut does not empty.

The only solution I can see is to reduce fat intake.

Ned Kock said...

Hi Shel, thanks. I am as surprised as you are about that bias against fruits. I too have never found any convincing evidence linking fruit consumption with any of the diseases of civilization.

Even Lustig made a point of saying that, while fructose in excess may be bad, that does not apply in any way to fruit consumption.

Apparently the combination of fructose+glucose found in fruits turns our liver into a “sponge” for blood sugar, increasing its insulin sensitivity:

Ned Kock said...

Thanks Jack for your insightful comments, as always.

Jack C said...

@ Peter,

Do you have a reference on the USDA article about carbohydrate consumption? I am curious to know where USDA got their data as they did not start tracking such things until 1970, and because the conclusion that there was no significant change in carbohydrate consumption between 1909 and 2000 is inconsistent with other estimates I have read that show a very large increase in carbohydrate consumption between those years.

USDA data shows that fat consumption constituted 43% of energy consumed in 1970 and 33% in 2008. During the same period total fat consumption remained relatively constant and the decrease in fat as per cent of energy, according to the USDA, was due to increased consumption of carbohydrates and protein. This indicates that carbohydrate consumption increased by over 50% between 1970 and 2008.

I have read estimates that fats constituted about 50% of energy intake around 1910. This estimate, which is admittedly fuzzy, seems consistent with USDA records between 1970 and present.

USDA data shows that animal fats were 61% of total fat intake in 1970 and 40% of intake in 2008.

Dr. B G said...

Hey Brutha!!

I am still waiting to see your critique and analysis which will show that wheat is more toxic and fatal than SMOKING in the China Study. * haa *

1/3 cup of white rice cooked is 15 grams (high GI naturally) -- not sure about that source quoted!

However I think when combined with vegetable fiber, fat and meat the glycemic index may alter but I have not come across any evidence yet. (maybe depends individually on the person's HOMA as well and response to carbs)

Jack C, I love all your insights. Also considering that a great majority of gluten/casein damaged individuals do not own functioning gallbladders, they cannot effectively process dietary fats well.


Ned Kock said...

Hi G. Unfortunately the China Study II dataset is a bit of a mess, so I haven’t been able to include as many columns as I wanted. I am referring to the China Study II dataset where data is provided by county, which I have been using. So smoking is not in it, yet.

rhinoplasty said...

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Ed said...

Does th china study break out a separate accounting of added sugar? You don't seem to be directly controlling for it. Cakes cookies brownies doughnuts etc are all typically sugar-laden wheat products. I wonder if the strong correlation with wheat might really be and indication of added sugar consumption.

Anonymous said...

What a load of crap.

Countries who base their caloric consumption on refined carbohydrates like Italy, have some of the lowest obesity rates in the world.

In contrast, countries who base their diets on animal products are chronically obese.

The guy who runs this website is pretty much another gullible shill doing his part in the america´s big deception.

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