T Nation

quick question

I know that fruit is insulin independent and that it is NOT conducive to eat fruit post-workout. I was talking about this with some family members a few weeks ago (a couple of which are diabetic). Anyways, once I stated that fruit is insulin independent they immediately thought they could eat all the fruit they want and not have to worry about thier insulin levels. I said whoa…wait a minute. The fructose still goes to your liver and is turned to glucose and your body will eventually have an insulin response. Was I correct in saying that??? I know that fruit is not a good resource for post workout nutrition, cause it is not “shuttled” into the muscles immediately. But it still goes to the liver and turned to glucose, which will then spike insulin later on…right??? Which in the long run…is NOT good for a type II diabetic. Does anyone have any input. cause I sure would like to know if I was right or not. Thanks…Tony G

Fruit generally also contains sucrose,
which is half glucose, and so these
fruits will directly increase blood
sugar.

You’re right that fructose can be
converted to glucose but, not dead
positive, I think this generally
results in increase in glycogen stores
in the liver or production of fatty
acids rather than directly increasing
blood glucose. It would stand to reason
that fructose performing these tasks
might reduce the liver’s utilization
of glucose, so consuming fructose
with glucose might cause a greater
rise in blood glucose than without
the fructose. Unfortunately I’m
speaking only in theory, when certainly
this sort of thing has actually
been measured, which would be by far
the better basis to go on.

In any case, diabetics do find a use
for pure fructose as a sweetener
having at least substantially less
effect on blood glucose than would be
the case with glucose or sucrose.

That’s a really good question, Antonio. However, you first must clarify that you’re talking about fructose and not just fruit. It is the fructose content that you should be concerned with. Now, fruit is not just composed of fructose, so that should be considered as well.

Fructose is metabolized by the liver and preferentially stored as liver glycogen. If liver glycogen stores are saturated, then you’re likely looking at triglyceride synthesis (i.e. de novo lipogenesis.

As far as for diabetics, I can only speculate as this is not an area of my concentration. Personally, I think that diabetics are one population of several that would do very well on a ketogenic diet.

Yeah, and don’t forget, fruit is healthy and has many benefits (vitamins, phytochemicals, fiber, etc.), so it shouldn’t be eliminated from the diet. I always suggest 2-4 servings per day as okay, even for those concerned with staying lean and mean. Just stick to low-GI fruit sources like apples and oranges if you’re worried about it.

A quick point on the subject of diabetics and ketogenic diets. You have to be extremely careful with this. Normal individuals with healthy insulin function have no problem with ketosis obviously. There is a feedback mechanism that protects us from diabetic ketoacidosis. Very high ketone concentration in the blood will stimulate an insulin release with the message to clear the ketones, thus preventing a hyperacidic state. However, Type 1 diabetics, with faulty insulin function don?t have this feedback loop, so in some cases, ketone concentration can get dangerously high.

Ketogenic diets might be good for Type 2/insulin resistant diabetic, but not for a Type 1 diabetic in my opinion. Too many variables.

Thunder, that’s a fantastic point. My blankent statement was too general, as a result of the fact that I ASSumed.

Thanks for clearing that up for everyone, as I am in complete harmony with that.

I would also like to see you around these parts more often, brutha!

I may be showing my lack of knowledge her, but does carbohydrates like yams and oatmeal also replace liver glycogen? About how much glycogen can the liver store?

J-Dog, starchy carbs like yams and oats are polysaccharides, which means they are long chains of the monosaccharide glucose. Glucose preferential restores muscle glycogen. I would imagine that as muscle glycogen stores become saturated, or as a large amount of carbohydrate is ingested, some glucose gets stored in the liver. However, the resynthesis of liver glycogen from glucose is not nearly the level of that of fructose.

The liver can store about 100g of glycogen, but the range is probably between 80 and 120g. In the absence of food, it takes approximately 24 hours for liver glycogen to become depleted due to the fact that the liver supplies endogenous glucose at a rate of approximately 5g/hour (i.e. 5g/hour x 24hours = 120hours). However, physical activity and exercise will accelerate this process, with the latter doing so considerably.

So if I am eating two apples a day, do you think I will have some spillover?

No