Carbohydrates as a source of energy ~ Eric Jequier, 1994

Carbohydrates as a source of energy
Eric Jéquier  Am J Clin Nutr 1994; 59(suppl):682S-5S.

Carbohydrates are the main energy source of the human diet. The metabolic disposal of dietary carbohydrates is direct oxidation in various tissues, glycogen synthesis (in liver and muscles), and hepatic de novo lipogenesis. This latter pathway is quantitatively not important in man because under most conditions the rate of de novo lipogenesis does not exceed the concomitant rate of lipid oxidation in the whole body.  Thus, dietary carbohydrates do not appear to increase an individual’s fat content by de novo lipogenesis. The intake of dietary carbohydrates mainly has the effect of inhibiting fat oxidation while glucose oxidation is increased. Dietary carbohydrates are involved in the control of energy balance because the regulation of food intake depends, in part, on the carbohydrate need of the individual.  Because there is an obligatory requirement for glucose in several organs such as the brain, a spontaneous increase in food intake is seen when the diet has a low-carbohydrate, high-fat content.  Therefore, the present nutritional advice of increasing the proportion of carbohydrate energy while decreasing that of fat in the everyday diet has strong scientific support in terms of the regulation of the energy balance.

Quite an interesting read.  More later.

Comments

J D said…
Wasnt that guy exposed to highly biased towards low-fat dieting? Ofcourse he would promote carbs in such a case.
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If/when you discuss this later, I'm hoping you'll address two things. First, to what extent can DNL be upregulated? And second, is hepatic DNL the only player wrt carb->fat?
carbsane said…
Good suggestions, will do!
carbsane said…
"Exposed"? By who and for what? Details!


In any case, that might put his conclusions up for debate, but not the science itself. Have his conclusions been challenged somewhere other than labeling him as highly biased. It is interesting that some of his work is used by Feinman and others if indeed he is such a biased scientist.
Victor Venema said…
Thus in 1994 it was not known yet that the brain could also use lactose and ketone bodies?
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grinch said…
Well his conclusions contradict all the free-living studies showing that low carb diets lead to greater spontaneous reduction in calorie intake over low-fat diets. Did he consider the possibility that once one becomes adapted to less carbs, their body demands less carbs or did he draw this conclusion based on subjects who were high carb eaters suddenly deprived of carbs?
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If 30% fat diets are being used as an example of low-fat, then it's a joke and probably reinforcing the actual crux of the point being made in the referenced paper. Of course in a hypercaloric diet with that much fat present, quite a bit of it is going to go into immediate storage due to the carbohydrate content.
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carbsane said…
I don't really know of any either. The LoBAG diet studies were short (5 weeks) and varied carbs (never VLC) in weight stable state in diabetics but that's about it. Here is where looking at the diets of relatively isolated cultures for generations can give better clues.
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grinch said…
This may be of use to you.

http://www.nutritionandmetabolism.com/content/3/1/24
screennamerequired22 said…
This was the one I was thinking about.

http://www.ncbi.nlm.nih.gov/pubmed/19328268
eulerandothers said…
This study looks interesting because although it's by Volek, it refers to and calls attention to the study by Krauss:
http://www.ncbi.nlm.nih.gov/pubmed/16685042

That looked interesting because there seemed to be nothing but references to saturated fat, not total fat. So, where does 'low-fat' figure in all of this, I wondered. It turns out they weren't looking at total fat as a crucial variable.

In the Krauss study, they gave the participants lunch and dinner and provided them with menus for breakfasts and snacks. All the subjects were men and chosen for their higher prevalence of LDL pattern B (that leaves me out!). All I can quickly glean from NCBI about LDL pattern B is that it means 'predominance of small dense particles', and distinguishes pattern A from pattern B,'pattern A (large, buoyand, LDL dominant) and B (sd-LDL dominant); I'm guessing sd means 'small density'. The Krauss study was 'designed to be able to detect a 50% reduction in the prevalence of LDL-subclass pattern B between groups.'

There was a relatively high carb period at the beginning of the diets. (basal diet).
Then, assignment to the same high carb (basal) diet or one of three low-carb diets.

The high carb (basal) diet was 54% carb, low saturated fat (7%) but 30% total fat.

The three low carb diets were:

39% carb-and low saturated fat (8%) but 31% total fat,

26% carb-and low saturated fat (9%) but 46% total fat,

26% carb-and high saturated fat (15%) but 45% total fat.



The participants stayed on these diets for 3 weeks (first stable weight period).


After that, they all had to reduce daily caloric intake by 1000 calories a day! Yeah, that's what I call a diet. For 5 weeks.


Finally, there was a weight-stabilization period in energy intake was adjusted to stabilize weight for 4 weeks (final stable-weight period).


The researchers were looking at LDL diameter. When the participants first adopted their diets, LDL peak particle diameter increased 'to a significantly greater extent with both the 39% and 26% carbohydrate, low-saturated-fat diets, than with the 54% carbohydrate diet.'
Notice that the 54% carbohydrate and the 39% carbohydrate diet both had nearly the same total fat percentage (30 and 31, respectively).


That LDL diameter aside, there were other 'lipoprotein differences' between the highest carb diet and the lowest carb diet by the end of the experiment. Weight loss and the following final stabilization period, 'led to reductions in each of these variables that were significantly greater with the 54% carbohydrate diet than with the 26% carbohydrate, low-saturated fat diet.'


That's surprising. I mean, I wonder if I read it correctly. Such is the power of weight loss, I guess.
carbsane said…
I agree with Kade, most LF test diets are not proper comparisons to LC -- they are often either too high in fat (why is it appropriate to compare 10-20% carb diets to 30% fat diets?) and/or not matched in protein and/or highly processed.


But I'm actually less interested in his conclusions/interpretations than I am in the figures on the top of the third page in terms of what happens when overeating.
Bris vegas said…
Back in 1994 dietary fat was verboten. A "healthy" diet according to many mainstream nutritionists was a bucket of steamed white rice or pasta every two hours.
Bris vegas said…
"All the subjects were men and chosen for their higher prevalence of LDL pattern B (that leaves me out!).'

in Australia tests for the various lipid particles are not even performed because there is no evidence that they are meaningful in clinical context.


In fact many Australian cardiologists think cholesterol measurements in general are pretty meaningless.
carbsane said…
Really? I don't recall that dietary advice.
carbsane said…
Seems you read this correctly. To Bris vegas, I think the particle size is losing ground as predictor to particle number. I think they mean well trying to find these predictive markers, but I wonder if changing them has ever been demonstrated to alter risk.
Bris vegas said…
You must have been in a coma then.

In 1994 the USDA recommended up to ELEVEN servings of bread, FIVE servings of (starchy) vegetables and FOUR servings of fruit per day. In other words a diet based almost entirely on (refined) carbohydrates.
http://www.ars.usda.gov/SP2UserFiles/Place/12355000/pdf/Pynet_94.PDF

High profile nutrition experts such as Dr Rosemary Stanton were recommending a MAXIMUM fat intake of 10% of calories with ~80% of calories as carbohydrates.
carbsane said…
A bucket of rice or pasta every two hours would be how much? A pint? A serving of bread is one slice = ~ 15g carb and equivalents given are 1/2c. cooked rice or pasta = ~20g carb. Veggies were not supposed to be starchy, you inserted that.

I'm not saying low fat wasn't pushed, but 10% fat was never mainstream. "They" couldn't even succeed in getting us to eat at around or under 30% total/10% sat fat.

This graphic is interesting though. I thought in 1994 we were all eating less fat ;-)
carbsane said…
Does anyone else see what's wrong with the pyramids above (e.g. the one on the right? which is supposedly what we were consuming as Americans in 1994)
carbsane said…
I was not familiar with Rosemary Stanton who is an Australian nutritionist. So I did a quick Google and look what turned up: Where is the brain of Rosemary Stanton? on Peter/Hyperlipid's blog. Interesting how Peter can trash someone insinuating she is an idiot with no brain function but he was the epitome of the respected science blogger at the time.

In comments, blogblog writes: I suggest you have a look at photos of famous nutrition "experts":
- Rosemary Stanton (very low fat diet) looks like a cadaver.
- Artemis Simopolous (Mediterranean diet)is extremly fat.
- Barry Sears (The Zone)is very flabby.
-Loren Cordain (paleo diet) is lean and athletic.

That was 2010. Might want to update the last description of Cordain. I don't know her age but Stanton certainly doesn't look like a cadaver in my Google Images searches. I would describe Sears as flabby (his tendency towards chin fat doesn't help in pictures), and Artemis Simopolous is overweight but "extremely fat"?

Then there's ThatPaleoGuy Jamie Scott talking about how the vegetarians were always slim and how oddly enough the eating disordered tend to go into nutrition including one anorexic, but he used to eat total crap but got away with it. He's been rather annoyed of late that anyone criticize the paleo ways. I guess he hasn't seen some of the paleo nutritionists lately :( Oh, and then there's Emily Deans commenting away having no issue with the tone of Peter's blogging attacking people personally and getting in a few digs of her own. We even get the assertion that Stanton lacks proper credentials -- Rosemary, not J. that is. As long as they're not paleo or low carb it's all in good fun, right?

For the record, I agree that the general appearance of those advocating for a dietary philosophy (or fitness regime) is fair game and relevant to the discussion. I don't think many vegetarian advocates look particularly healthy, but the same goes for various WAPF, paleos and low carbers. This should be discussed with some level of consistency and evenhanded objectiveness. The same goes for credentials. Some of what passes for credentials in the paleo community would be roundly laughed out of the room in any serious gathering.

Three years on and it's interesting to look around and see how many of the pretty paleo people are eating disordered and suffering from adrenal fatigue (and outright anorexic) as a result of their nutrient packed healthy diets ... oh, and running around (when they have the energy, usually requiring caffeine) blaming their low fat diets of years ago for being broken. They then commit to be even more strict in their paleo ways, because doing more of the same thing and expecting a different result is generally encouraged. Nah. Let's not shine ANY lights there. Just pass the tequila!
carbsane said…
It would be difficult to fatten a human on just tapioca, but I suppose anything is possible with enough force feeding. I'd need more details to comment one way or the other on that.

There is some interesting stuff in your second link. The first is the rates of DNL with hyperinsulinemia independent of carbohydrate intake. Reference 4 from there (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC185982/pdf/jcinvest00018-0200.pdf) has Marc Hellerstein as an author and I believe I discussed that paper here (though perhaps not, just in comments). Hellerstein is the big gun who has done a lot of radiolabel work on DNL and is oft cited (still) as saying that it is not a significant metabolic pathway. I do find the HIV-hyperinsulinemia-DNL very interesting.


DNL in adipose tissue appears to be VERY important from a metabolic standpoint, but I'm not sure it is as important in contributing to lipid stores (one way or the other). Lots to discuss, hopefully I can get to it. I really want to get back to the other diabetes review paper I've been meaning to discuss first.