Body Won’t Process Calories From High-fat Diet, Says LSU AgCenter Nutritionist

[Viking Dan]

http://www.agctr.lsu.edu/en/communications/news/news_you_can_use/Body+Wont+Process+Calories+From+Highfat+Diet+Says+ LSU+AgCenter+Nutritionist.htm


A study conducted by Drs. Steve Smith, Robert Koza, Mathew Hulver and George Bray from Pennington Biomedical Research Center looked at how a high-fat diet influences energy production when individuals consumed a high-fat diet.
Ten healthy young men were fed a diet where half of the energy came from fat. "That’s a very high-fat diet," Roy says, "considering that normally about one-third of energy comes from fat."
The subjects ate the high-fat diet for four days. In that short time, the energy-producing pathway in the cell changed and became less productive because of the high-fat diet. Some aspects of the pathway were reduced more than two times from normal level. The same results were obtained in animal studies.
"These results are somewhat surprising," Roy says, explaining, "Normally one would think that if fat intake is increased, our energy pathways would increase fat use since more of it is now available. But that is not what happens."
Why that happens is not known.



That's mildly disturbing. Why is that? Fat levels not high enough? Carbs not low enough? Both?

[mcsblues]

I would say at least a partial answer is that four days is nowhere near long enough to adapt. Four weeks or longer is generally regarded as the sort of timeframe we need.

[mcsblues]

This is not exactly the same study - but some of the same authors are involved - this time the study duration was only 3 days (although a further experiment with mice was for 3 weeks)

http://diabetes.diabetesjournals.org/cgi/content/full/54/7/1926

[Viking Dan]

I would say at least a partial answer is that four days is nowhere near long enough to adapt. Four weeks or longer is generally regarded as the sort of timeframe we need.

How long is required? Does one have to be in ketosis to adapt entirely?


This is not exactly the same study - but some of the same authors are involved - this time the study duration was only 3 days (although a further experiment with mice was for 3 weeks)

Thanks for the link. It would probably help me if I knew what Mitochondrial Oxidative Phosphorylation was. Ah well. Google is my friend...

[LisaS]

mitochondrial - having to do with mitochondria (a cellular organelle)
oxidative phosphorylation -
essentially the oxygen-dependent metabolic steps which produce energy/ATP -- basically the reactions of the ETS (electron transport system)

when the article talks of "complex I" "complex II" -- you'll see them in this cartoon
http://www.gwu.edu/~mpb/oxidativephos.htm

so in that 2nd study, they looked at the gene expression and gene products that are involved with mitochondrial metabolism (e.g. the ETS (last steps of burning sugar or fat)) and wanted to know if there was more or less gene expression / production of these products in response to a higher fat diet.

[Gabriel Guzman]

Well, without having read the actual study one has to wonder if whoever wrote that piece (not the study but the link) understood and what the study really did. For starters, it's not enough to say 'half of the enrgy came from fat' without saying how much carbohydrate was present in the diet. Assuming that the protein part of the diet remained as low as 15% as it is usually the case, then the rest was carbohydrate and then we would have to know which carbohydrate source (the effects of sucrose and fructose are different enven though they're both effective carbohydrates). Anyway, the point is that if the body is not used to use fat for energy, it doesn't matter if fat is increased in the diet, the body is still ineficient to use it. If, in addition, there is more than enough carbohdyrate so there is plenty of insulin around, fat won't be used for energy but it will go to the stores instead.

Also as noted on posts previous to this one, it's difficult to conclude anything from 3-4 days on a diet that the body has never seen.

[LisaS]

yes, they seem a little skewed in the write-up/article.
I did read whatever study it was that was published in the link from mcsblues - and what I found interesting was their "take" in the discussion - essentially that changes seen in *starvation* were also seen in response to *high fat* and wasn't it interesting that *the body reacts to high fat as if starving* (not a direct quote - but you could hear their ALARM over this)

--- WHAT? Why isn't it just as interesting to say when the body is burning/using stored fat or dietary fat it looks like *this* - whether from a higher fat diet or extreme deprivation?
-- and that is, as you say, only if the alleged changes seen are even real, sustained and relevant --

[Gabriel Guzman]

I think that there are people in the research arena who still think of starvation ensues in a very short time and has something to do with not getting enough glucose for fuel. They have a little more reading to do.

True, when people decrease their carbohydrate intake the first signal for the cells is that they're not getting enough energy from their preferred source, which in turn triggers the mechanisms to make the switch to an alternative source, fat. But the cells never really starve.

Also, there is this tendency to use the word 'starvation' so lightly. An overnight fast is not starvation. A prolongued period of fasting may become 'true' starvation. Every time I hear experts talking about people putting themselves in 'starvation mode' because they're cutting down their carbohdyrate, I really want to shake their heads so maybe their brains would really process the idea that true starvation is something else.