T Nation

Lipogenesis, Fact or Fiction?

This idea that the body will upregulate its carbohydrate metabolism to keep pace with carb consumption, with the result of very little, if any, lipogenesis taking place is being argued by JMoUCF87 based on a couple of studies. Now it’s interesting that when he was asked how this theory was working out for himself or his clients, he went into a tyrade about not needing clients or even needing to train in order to be able to use “logic” to figure something out. He said he’s just a guy how likes to “talk nutrition”.

I’m sorry, but this is the same guy how believes that as long as you get your requsite calories and macronutrients, it doesn’t matter where they come from! A guy, in sarcasm, responded to his carbs don’t cause lipogenesis rant by saying he was going to slam some skittles and pop-tarts and get shredded. Our resident expert said, in all seriousness, “sounds good to me, as long as you’re getting your macros”!

This is the same guy I had a long disagrement with on the “If You Want to Eat Pure Food, You’re Crazy” thread. In a nutshell, this guy basically argues against everthing we at T-Nation take as foundational to a sound, sensible, life.

P.S. he also advocates for the authors who (apparently) were attacking the claims behind the “I, Bodybuilder” program–which hasn’t even been published yet. Granted, I know nothing about McDonald or Aragorn.

Crowbar

[quote]Bill Roberts wrote:
Vegita wrote:
MODOK wrote:
I’m confused…are there people who are claiming lipogenesis doesn’t exist? Thats so bizarre I don’t even know how to respond. Go down to the IHOP and you’ll actually see it happening before your eyes!

The theory is that in humans, Lipogenesis is not as profound as one would assume. The effect of people getting fat seems to be that carbs shut off fat burning so when a mixed meal is consumed, nearly ALL of the fat intake is stored as bodyfat. Using this theory, one could consume considerably more carbs on a daily basis, and avoid consuming them with fat and bodyfat storage would be minimal. However it seems as if there is still a grey area when it comes to the role of adipose tissue and lipogenesis rates occuring in them. I think the study I posted used figures that if you ate 500G carbohydrate meal, only around 5 grams is converted to fat via lipogenesis. So not that it doesn’t exist, but that it doesn’t happen to the extent previously thought. It’s just a theory, but it does make JB’s guidelines more scientifically relavant.

V

So what happens to the 2000 calories?

BMR goes up by an extra 2000 calories over those few hours?

I really don’t think that’s the case.

Let’s say glycogen stores are nearly full. If so, then where does this matter go, if not to fat?

The carbs are not going out the urine, the feces, the breath, or sweat as such.

[/quote]

This is exactly why I want to search out and find more studies. It seems to me the study is implying that metobolic rate increase may be responsible for burning the calories. But I think they leave the door open enough to suggest that adipose tissue is running Lipogenesis at a higher rate than the liver is and may be storing some extra, just how much I think is still an unknown to this point. Unless I or anyone else can find a study where it is actually covered.

V

Why would it even be thought that all or most lipogenesis occurs in the liver?

Fat cells are not known to uptake glucose? (They are.)

Or why, if someone grants this uptake of glucose, would it be imagined that it remains glucose in the fat cells? (It doesn’t.)

Fact. Simples! :wink:

[quote]Bill Roberts wrote:
If nothing else one can rely on some very basic and unavoidable facts.

The only things that can happen with carbohydrates, fat, or protein once absorbed into the bloodstream are:

  1. They can be burned, yielding CO2 and water (or also ultimately) urea, and thus eliminated from the body. Or

  2. Their mass can be incorporated into the body.

Absorbed fats, carbs, and protein can’t be breathed out (except after being burned), pissed out (except for the nitrogen content in protein after being burned), or escape via the ass. A small amount is lost from shed skin and hair but this is not important: there is also some nitrogen loss in sweat but I am not sure if this before or after protein is burned, or both.

So in other words if calories are absorbed the amount in excess of what is burned IS going to go to increased weight, usually fat. And the idea that the amount that is burned will automatically go up to match intake pretty much no matter what it is, is not correct. In fact it generally is not true at a 1:1 ratio for anything about usual maintenance. That is to say, the thermic effect of added food beyond usual maintenance is normally not fully equal to the added calorie intake.

There is no magic way for them to have some other fate, such as in the radio ads for thermal wrap treatments that supposedly result in major fat losses and “shrinking of fat calls” from a single treatment. (Where does the fat supposedly go? Does the starship Enterprise cruise by and beam it out?)[/quote]

Forgive the lack of sophistication but since when do we not poop carbohydrate, protein or fat? Were I to eat 500g of peanuts, I will poop chunky peanut butter. If I eat a blow-out carb meal, I well… I’ll spare you the details.

[quote]Bill Roberts wrote:
Why would it even be thought that all or most lipogenesis occurs in the liver?

Fat cells are not known to uptake glucose? (They are.)

Or why, if someone grants this uptake of glucose, would it be imagined that it remains glucose in the fat cells? (It doesn’t.)[/quote]

We learned in A&P that it occured in the liver. Thats what the professors and textbooks said.

V

I’d suggest that before working so hard to try to support a conclusion which is crazy, just consider the fact (I believe it is a fact) that no study has ever shown a thermic effect of food in man on the order of increasing RMR by very many hundreds of calories per hour, which is what would be required to deal with your 2000 calorie example.

Until finding evidence of such an extreme thermic effect of food in man, the conclusion you seem to be striving to swallow camels to try to find support for, rather than straining out the gnat, should I think be viewed as probably (as in 99.999%) wrong. Namely, consuming 2000 calories of carbs in a short time, regardless of no fat being consumed, when glycogen stores are full and let us say the body is essentially at rest or only lightly active will result in that, or that minus RMR over that period of time and workload and some modest increment, will be converted to fat.

Which is why the stuff-your-face-with-sugar-or-carbs-and-it’s-fine-so-long-as-there-isn’t-fat-at-the-same-time diet does not work (I am sure you cannot find a person who needed to diet for whom it has.)

You accidentally skipped over my phrase, “absorbed into the bloodstream.”

The peanuts you refer to were not absorbed into the bloodstream and then, after this, excreted as peanuts in the feces.

[quote]Kvetch wrote:
Bill Roberts wrote:
If nothing else one can rely on some very basic and unavoidable facts.

The only things that can happen with carbohydrates, fat, or protein once absorbed into the bloodstream are:

  1. They can be burned, yielding CO2 and water (or also ultimately) urea, and thus eliminated from the body. Or

  2. Their mass can be incorporated into the body.

Absorbed fats, carbs, and protein can’t be breathed out (except after being burned), pissed out (except for the nitrogen content in protein after being burned), or escape via the ass. A small amount is lost from shed skin and hair but this is not important: there is also some nitrogen loss in sweat but I am not sure if this before or after protein is burned, or both.

So in other words if calories are absorbed the amount in excess of what is burned IS going to go to increased weight, usually fat. And the idea that the amount that is burned will automatically go up to match intake pretty much no matter what it is, is not correct. In fact it generally is not true at a 1:1 ratio for anything about usual maintenance. That is to say, the thermic effect of added food beyond usual maintenance is normally not fully equal to the added calorie intake.

There is no magic way for them to have some other fate, such as in the radio ads for thermal wrap treatments that supposedly result in major fat losses and “shrinking of fat calls” from a single treatment. (Where does the fat supposedly go? Does the starship Enterprise cruise by and beam it out?)

Forgive the lack of sophistication but since when do we not poop carbohydrate, protein or fat? Were I to eat 500g of peanuts, I will poop chunky peanut butter. If I eat a blow-out carb meal, I well… I’ll spare you the details.[/quote]

[quote]Vegita wrote:
Bill Roberts wrote:
Why would it even be thought that all or most lipogenesis occurs in the liver?

Fat cells are not known to uptake glucose? (They are.)

Or why, if someone grants this uptake of glucose, would it be imagined that it remains glucose in the fat cells? (It doesn’t.)

We learned in A&P that it occured in the liver. Thats what the professors and textbooks said.

V[/quote]

It can be an error to extrapolate too far.

If you had asked the professors if whether lipogenesis occurs in fat cells when blood glucose levels are high, they would have told you, generally yes.

To find some information relevant to this, you could find abstracts and probably some free full-text journal articles on diabetes which refer to the importance of adipose tissue on regulation of blood sugar levels. What happens to the glucose on absorption by this tissue is converion to fat.

[quote]Bill Roberts wrote:
You accidentally skipped over my phrase, “absorbed into the bloodstream.”
[/quote]

Ah. Whoops. Carry on.

Anyway, it seems that Parillo-ism lives on! :wink:

Minor note – in seeing one of my above posts I noticed that it was imprecise:

[quote]The only things that can happen with carbohydrates, fat, or protein once absorbed into the bloodstream are:

  1. They can be burned, yielding CO2 and water (or also ultimately) urea, and thus eliminated from the body. Or

  2. Their mass can be incorporated into the body. [/quote]

Not all of their mass. For example if glucose is converted to fat, much water is released and does not, long-term, add to body mass as it is readily excreted or lost to the breath or sweat.

But all of their carbon mass, yes, if not burned, and a lot of the hydrogen mass and some of the oxygen mass.

First off, as I admitted in the other thread, I’m no expert on this topic. My degrees are in chemical engineering. So my understanding of biological systems is pretty basic compared to all of you.

There was another study from that other thread that I found interesting. They did this on human subjects (two groups, lean and obese). They took these subjects and fed them a controlled diet for 3 days to “baseline them” (sounds like only for the lean group). Then the morning of the 4th day, they were all monitored for 15 hours straight in a ventilated hood using “continuous respiratory exchange measurements”, urine was monitored, body weight, blood samples were periodically for insulin, glucose , free fatty acids, blood-urea nitrogen. During this time, they were fed 500 grams of dextrin maltose & fruit juice in three portions.

They claim:

  1. The carbs were either oxidized or stored as glycogen
  2. The thermic effect of the carbs was less in the obese group than the lean
  3. They cite another study in which the “adipose tissue triglycerides reflects the type of dietary fat consumed”
  4. Carbohydrate consumption favors accumulation of dietary fat by reducing the rate of fat oxidation (it’s inhibited after carb intake.

If it doesn’t automatically download the pdf, click the manual download link to the left:

One problem I had with the study is that 500 grams of carbs is only about 2000 kcals. Sounds like they didn’t use enough juice to make it much more than 2500 kcals. They weren’t feeding these subjects massively over their energy requirements. Granted the subjects were just sitting around for 15 hours, but their energy requirements couldn’t have been too far off from 2000 kcals.

For those of us near, or slightly above maintenance, it does seem to supports carb cycling and P+F or P+C approachs. It also may support the following statements:

  1. Carbs should be eaten early in the morning and peri-workout to replenish glycogen stores (this has been talked about extensively on the site)
  2. Each individuals “carb sensitivity” may be a function of how much glycogen they can store
  3. Carbs are used preferentially over fat
  4. You need to have periods of no carb consumption to burn fat for fuel.

So, while I’m still not clear on if lipogenesis does occur to glycogen if carbs are consumed in excess, this has really made me think a lot more about why carb cycling and macro partitioning work.

Bill, I’d be really interested to hear your take on this study. Especially if there are some glaring oversights in their methodology or conclusions from their data.

I have at the moment only glanced at it.

But for presently (and there might be nothing on further in-depth reading) their figures show glycogen increase of 315 g, out of the 500, in the non-obese subjects, and pretty similar in the obese.

I was careful to specify that I was referring to situations where glycogen stores were full.

So what was shown was not that energy expenditure increases to match grossly excessive carb intake, but rather that when glycogen is not full, replenishment can be at the rate seen.

Nothing here shows or to me suggests that chronic carb-overfeeding, whether in the absence of fats or not, does not result in lipogenesis in adipose tissue coming close to matching the excess in caloric intake.

The study doesn’t at at all refute that the macronutrient must either be burned or will be stored, and does show that thermic effect did not result in amount of increased metabolic rate sufficient to match the high carb intake. Rather storage did occur, of what was not burned at the time, which was at quite an ordinary rate.

In this case storage was as glycogen, but with reference to long term intake in excess of calories burned that will not be the case, as only so much glycogen can b be stored.

On your point 4, it isn’t correct. Countless people have lost fat while having carbs with every meal. I’ve lost far while having carbs around the clock (I’ve dieted down while having sleep problems and having a small meal with carbs twice during the night, as well as frequent small meals during the day.

[quote]Bill Roberts wrote:

On your point 4, it isn’t correct. Countless people have lost fat while having carbs with every meal. I’ve lost far while having carbs around the clock (I’ve dieted down while having sleep problems and having a small meal with carbs twice during the night, as well as frequent small meals during the day.[/quote]

Yeah good point. I have too. Obviously you need to be in overall calorie deficit. In that case is it correct to say that the body would have consumed available glucose and liver glycogen before going after the fat stores? Or does the body pull both glycogen from the liver and fat from fat cells to fuel the body in calorie deficit?

The processes will be occurring at the same time but at different rates.

So in other words, when in a caloric deficit, glycogen is being converted to glucose and burned, and also fat is being burned.

For example this is seen when analyzing respiratory gases in aerobic exercise done on an empty stomach (or not-empty, for that matter.) Fat and carbohydrate are both burned at all times.

Now the figures I’ve seen on that were not from individuals who had been on a ketogenic diet for an extended time, but I expect it would be true even in their case (the glucose would come via gluconeogenesis from amino acids, whether from dietary protein or catabolism of muscle protein.)

Thanks Guys, I am learning a lot right now. So basically the studies are inconclusive because they are not overfeeding carbs, thus just because they aren’t converting in a significant way to fat, only means they are being stored as glycogen. Makes sense, so to really find out for sure a study would need to be done on fully fed individuals, and then have them overfeed on carbs, and preferrably have one group also overfeed on carbs and fats to see what happens.

V

Yes, exactly.