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(vagrant @ Feb. 28 2007,10:02)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">I don't read the journals. I did read my endocrinology textbooks, understand the process, and went from there.</div>
heres the problem, and it relates to what I wrote origonally
which was
<div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">
The body can turn carbs into fat, and can turn amino acids to fat, it just doesnt happen except under very specific cicumstances</div>
Endocrin texts show the pathway, not the actual utilization of this pathway.
Denovolipogenesis is the pathway that is less traveled.
The body can use this pathway, its just that it doesnt use it a whole lot, as it is energetically worthless to do so, and the body loves conserving as much energy as possible.
Carbohydrates blunt fat oxidation, blunt lipolysis and increase esterification in the adipocytes. So if you burn less fat, and you eat more fat, the fat you are eating gets stored. Eat enough carbs and every piece of fat you eat will be stored, and you get fatter. This does require a positive energetic balance as well.
When providing the body with a large bolus of monosachharides or similar, de novo lipogenesis starts to raise, but even with 500g of malto your talking around 4-5g of fat produced, hardly measureable in the whole body. And to lead to a increase in body fat mass, this has to totalled into an overall fat balance (as 4-5g produced can be lost to the postprandial periods energy requirements) and ultimately bodyweight. 4-5g is well below the theoretical energetic efficiency of carbs->fat with is 10g carb = 3g fat)
Typically the situations that DNL start getting higher are within massive carbohydrate overfeeding (some trials look at something like 1500+grams of carbs per day, but typically overfeeding subjects with around 500grams of extra carbs). Extreme low fat, high carb diets can increase carbohydrate -> fat lipogenic pathways, but within modern society with 30+% fat/total energy tis not a reality.
To quote Hellerstien from his piece "No common energy currency: de novo lipogenesis as the road less traveled"
<div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">Because storage of energy as lipid is much more efficient
than storage as carbohydrate, the presumption has been that animals use de novo lipogenesis as a metabolic safety valve for storage of carbohydrate energy present in excess of carbohydrate oxidative needs (ie, carbohydrate energy surplus). On the basis of this presumed role, inhibitors of de novo lipogenesis
[such as (–)hydroxycitrate, an inhibitor of ATP citrate (pro-S)- lyase] have received attention as potential therapeutic agents for obesity and hyperlipidemia.
Most experimental data in humans, however, contradict this view of the function of de novo lipogenesis. Initial studies in which indirect calorimetry was used showed little or no net de novo lipogenesis after short-term carbohydrate overfeeding (1). Subsequent isotopic studies confirmed the absence of quantitatively significant flux through hepatic de novo lipogenesis under most conditions of carbohydrate energy surplus (2, 3).</div>
and the fun piece
<div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">First, these results do not mean that extra carbohydrate energy represents “free” energy in terms of body fatness. By sparing fat in the body’s fuel mixture, surplus carbohydrate energy will make people fatter, even though it is not directly converted to fat.</div>
