T Nation

fat, carbs, and insulin


#1

berardi says that fat slows the entry of carbs into the bloodstream, yet fat increases the insulin response of the carbs.

ok, insulin response is all fine and dandy, but if you're slowing the digestion of the carbs, then you reduce the glycemic load. i think most of us are aware that glycemic index doesn't mean everything.

so are you increasing the glycemic index of the carbs but also lowering the glycemic load? if this is the case, then i don't see berardi's point.


#2

JB's bottom line:
"So, knowing that fat appearance can be peaking (on average) 1-2 hours after ingestion, you can see that there will be a decent overlap in the time courses of appearance of fats, glucose, and insulin in the blood when a significant amount of carbs and fat are ingested together. Add to this the fact that carbohydrate and fat ingestion seems to lead to a synergistic increase in insulin response, and we're talking about some kickin' insulin."
'nuff said?


#3

The point is that increased glycemic index does not equal a larger release of insulin if less is entering the blood.

if the carbs are digested slower due to fat, you don't get a sudden rise in insulin. this would make the carbs more 'time release', which means the pancreas doesn't have to secrete as much insulin.

now, according to berardi, fat increases the glycemic index.

but an increased glycemic index with a lower amount entering the blood does not equal huge insulin response.

it's like watermelon...very high GI, but low glycemic load because there isn't a whole lot of the sugar in a serving.

so if you reduce the amount of carbs entering the blood but also increase the glycemic index, don't you end up about even?

berardi himself even said there's no science to back up this premise.


#4

Morg, there seems to be a lot of wishful thinking in your post:

"if the carbs are digested slower due to fat, you don't get a sudden rise in insulin. this would make the carbs more 'time release', which means the pancreas doesn't have to secrete as much insulin."

Unfortunately it doesn't happen that way, and there IS lots of evidence that shows it. The carbs are more "timed released" and so is insulin, but in greater amounts. If you were exercising after, you might burn more carbs as they come so the pancreas would not have to secrete as much insulin, but then you'd be exercising so insulin spike wouldn't matter anyway.

"Glycemic load" just means amount of carbs. If there is less carbs in a meal that does mean less insulin, that's true, but that has different implications depending on the whole diet. If you're bulking with let's say, 5 high fat meals each containing 25 grams of med-GI carbs, you'll probably put down more fat and have less calories the bodies can use for muscle growth then if you started the day with two meals of sixty grams of med GI carbs. That's the kind of comparison for which Berardi is saying the laboratory evidence is not in yet, not the effect of fat on the insulin response of a meal.


#5

Glycemic load is the total sugar content of a food, regardless of how slow it enters the bloodstream.

Glycemic index is how fast these sugars enter your bloodstream.

Don't confuse one with the other. The only way you increase the glycemic load of a certain food is by, well, eating more of it!


#6

Morg you have a lot of reading to do.

You're confusing simple concepts left and right.

Fats will REDUCE the glycemic index of a certain food by slowing the rate at which sugars appear in the bloodstream. BUT once in the bloodstrea, Carbs+Fats will have a synergistic effect on insulin release.
As has been said, the glycemic index beens little to you. What matters is how much INSULIN will be released in response to eating a certain food. Fats will lower the GI of a food by slowing down its digestion and thus the rate at which sugars are released into the bloodstream. But they will cause a higher insulin response because fats and carbs act synergistically on insulin release.


#7

And Brian, Glycemic Load does not necessarily mean a lesser insulin spike.

If you eat 15 grams of carbs from pure Dextrose, or 30 grams of carbs from Brocolli, which do you think will spike insulin higher?

That's right. There are several factors that determine how much insulin needs to be released:

  1. Glycemic load
  2. Insulin Index
  3. Food Combinations
  4. Timing of meal
  5. Your own Insulin Sensitivity

As far as Insulin levels go, GI is a poor predictor of it. Milk for example, has a very low GI but a fairly high Insulin Index.
Other foods cause a spike in blood sugar levels, but stimulate a lower insulin release.

That's why GI is quickly being replaced by the Insulin Index (although those Lab Rats sure could speed up the process a little more, lol).


#8

ok, so i have my terms confused.

that doesn't change things. diesel, you say that fat slows the release of carbs into the bloodstream. do you agree that if it slows the release into the blood, then the GI is reduced?

so first you lower the GI, and the carbs have a reduced GI for a while before the fat even enters the blood. this is a good thing, no?

now, once the fat gets into the blood, insulin is increased for a while. but where is the proof that this insulin repsponse is higher than carbs alone? saying carbs and fat increase GI in the blood doesn't show the whole picture.


#9

diesel, ok, another thing...if gylcemic index isn't a good guage, then why is berardi using it as evidence?


#10

Berardi has repeatdely said GI is next to useless.
Insulin Index (I) is what you need to pay attention to, but there has been little research done on the subject so far. The biggest list I've found on II has a mer 20 foods or so.

It's interesting to note that salmon has a moderate insulin index, and it has no carbs.


#11

diesel23, I meant lower glycemic load means less insulin, all else equal.

Morg, you write:
"so first you lower the GI, and the carbs have a reduced GI for a while before the fat even enters the blood. this is a good thing, no?"

Not necessarily. A lower GI may reduce the peak insulin released and slightly reduce amplitude of total postprandial insulin, but it will also increase the duration that insulin is around. But when following Massive Eating it's probably a good thing since with your P+F meal 10 grams of low GI carbs (excepting lactose) should have less of an insulin effect than 10 grams of high GI.

"now, once the fat gets into the blood, insulin is increased for a while. but where is the proof that this insulin repsponse is higher than carbs alone?"

It's on PubMed.


#12

And Morg, Berardi is using the GI as "evidence" of the rate of appearance of carbs in the blood. That's because it IS the rate of appearance of carbs in the blood.

Diesel didn't mean to convey to you that the GI is TOTALLY worthless. In general, for a given amount of carbs and carbs ONLY, the amount of insulin released is proportional to the GI of those carbs. In other words, the GI is our best substitute for an II until that expands.


#13

Let's assume that Berardi is right, that fats+carbs do cause a synergistic release of insulin. That means that the combination produces HIGHER levels of insulin that either one does by itself. And let's assume it's also true that fat SLOWS this release of insulin.

Here are 2 factors to consider:
1) RATE of insulin elevation
2) SIZE of insulin elevation

If you eat fast-acting carbs, where the rate of increase is high, you will quickly be in fat-storing mode (unless insulin sensitivity, muscle's receptivity to storing the blood sugar, is also high and the muscles can suck up all or most of the sugar, such as post-workout).

If you slow down the rate by adding fat, you will more slowly enter fat-storing mode. But whether it happened quickly or slowly, storing fat is storing fat! And now perhaps you have the potential to store even MORE fat, because by adding fat to the meal, an even higher amount of insulin was ultimately released.

morg, it looked to me that you were considering only the effect of rate. Berardi seems to be saying, though, that a HIGH LEVEL of insulin will be fattening. This makes sense, because high amounts of insulin will drive sugar into the fat cells (unless the muscle cells are highly sensitive to it, such as post-workout).

So, you can have a fast+high insulin release (sugary drink like Coke on an empty stomach) or a slow+high (pasta alfredo); both are potentially fattening. The slow+high is maybe even more fattening 'cause the high is higher. What we are trying to achieve in our diets is the slow+low insulin effect. Just enough blood sugar to feed our muscles' limited capacity and energy needs, not so much that excess sugar gets stored as fat.


#14

Very simply, dietary fat in the presence of high insulin gets stored and prevented from being used for energy.

Pasta and chicken, the carb calories will mostly be burned for energy.

Pasta and chicken and cheese, the carb calories will mostly be burned for energy and the fat calories will store as fat.

Chicken and cheese may assist the utilization of dietary fat for energy SOMEWHAT.


#15

"Acylation stimulation protein (ASP) is the real player in triglyceride synthesis in the fat cell. It is stimulated by the mere presence of chylomicrons in the bloodstream and is insulin indepdendent. So whether you eat your fat with carbs, protein or by itself, the dietary fat is going to get stored. Separating it out from carbs isn't going to make a shit's worth of difference."


#16

dietary fat will be stored? what is this, the '80s?


#17

Hey morg, no one has mentioned it yet, but great question! You really got some good info flowing here.
One problem though; no pictures!:slight_smile:


#18

I agree with morg in that the ASP post seems a "little dated", if not downright silly. Where is the quote from? It sounds like a cell biology lab tech is trying to get practical (and failing).


#19

I'll just ditto what andersons said. It was really well said.


#20

Hey Morg, its not the 80's but there is a reason why fatty acid composition of adipose matches the fatty acid composition of the diet,

because its the fat that you eat, that is stored, lipogeneiss from other sources is relatively insignificant