GI/GL - A Hopefully Constructive Discussion

PeachyCarol

I've seen quite a few mentions of the GI/GL lately on the boards, and I was wondering if we could have a CONSTRUCTIVE discussion on the science of it to help new users get to the bottom of it.

Here's what had me wondering, based on my personal experience:

I remember, in my years of dieting, hearing all the noise about the whole thing, and at some point when I was adding some carbs back into my life, I decided they'd only be lower GI carbs. So... no potatoes, even though I loved them. Just boiled sweet potatoes instead. Stuff like that.

As time went on, I said enough of that noise and just ate white potatoes again.

A funny thing happened. Well, nothing happened.

I learned more about how the studies had been done to find out the GI/GL of foods, and well, I wasn't just sitting down and eating a potato. I was eating it on top of my lentil shepherd's pie, or under some lentil chili or twice baked with some cottage cheese.

Have any studies EVER been done on the impact of any of the high GI/GL foods when eaten in combination with other foods?

I'd love to see some more actual science on how people REALLY eat.

DeguelloTex

My understanding is, I think, similar to yours. The foods are tested in isolation and in a fasted state. You know, like pretty much no one on earth eats.

juliebowman4

This newbie doesn't even know what GI or GL is.......

DeguelloTex

juliebowman4 wrote: »

This newbie doesn't even know what GI or GL is.......

Glycemic index, glycemic load. Or at least that's the way I'm reading it.

PeachyCarol

I know there's some mention on satiety with it, but there's also a study that shows potatoes (a notoriously high GI food) to be one of the most satiating foods.

It's very confusing to have conflicting data posted on the boards like this.

I personally find meals with potatoes in them to be very satiating.

yarwell

GI = Glycemic Index - the amount of blood glucose increase from eating 50 grams of carbohydrate from the given food relative to a test food defined as 100 - either glucose or white bread.

GL = Glycemic Load - grams of carbohydrate multiplied by GI / 100.

Usually measured on individual foods but can be measured on a meal or combination of foods. Sometimes combined mathematically as testing a food on 50 volunteers us costly and inconvenient.

eDonatti

High GI food increases blood sugar (if I remember correctly) resulting in a release of insuline disproportionally higher than needed. As a result insuline lowers blood sugar to a level that is too low resulting in feeling hunger. So my guess is if you eat high GI food with other food that slowly releases energy the sugar level doesn't go down as much because the other food is offsetting the insuline outburst so insuline 'doesn't take too much sugar out of your bloodstream'.

Or I'm getting this all wrong since I only heard about GI some time ago and never followed that through.

yarwell

Satiety is addressed in a recent review with many references http://www.sciencedirect.com/science/article/pii/S0924224414002386

Talks more about fibre than GI but links to a paper that digs into it a bit more - http://m.ajcn.nutrition.org/content/76/1/281S.full

Sabine_Stroehm

I don't have much in the way of scientific data, nothing you wouldn't already know. Like you, a potato didn't do much for my hunger, cravings etc.
White rice, while tasty, left me hungry soon after (aren't there jokes about that?), but no real cravings.
Heavily refined carbs almost always activate cravings for me, and often lead to an over eating/over indulging day.
So I limit them.
If I'm tired, or PMSing, or my reserves are otherwise depleted, it's even more likely I'm inhale a bag of whatever is around refined carbs wise. So I limit them, and limit when they are in the house.

It works well for me, and is a pretty damned easy way to maintain my weight (and it was a very easy way to keep on track when I was losing weight, since I was eating well, and not hangry.)

abatonfan

I found GI to be absolutely worthless for me. Steel-cut oatmeal is supposed to be low-GI (55), but it spikes my blood sugar much worse than higher-GI foods. I can't eat plain steel-cut oatmeal without experiencing BG excursions into the 250's, while most other foods only cause me to go up into the 160's.

PeachyCarol

yarwell wrote: »

Satiety is addressed in a recent review with many references http://www.sciencedirect.com/science/article/pii/S0924224414002386

Talks more about fibre than GI but links to a paper that digs into it a bit more - http://m.ajcn.nutrition.org/content/76/1/281S.full

Thanks for that. I dug a little deeper into the second one, and got excited when I saw them mention meals, but when I looked up the cites, the studies weren't quite what I was hoping for.

They were set up to compare purposefully low GI foods (a veggie omelet with a piece of fruit) vs. steel cut oats with fructose and milk (the medium GI option) vs. instant oatmeal sweetened the highest GI way possible with milk that had some enzyme added to it to increase its GI.

That was the first mention of meals citation. So I read on. I saw a second. I checked. Same study author, but it mentioned breakfast AND lunch, so I thought it might be different. Nope. Same meals offered again, and they repeated breakfast for lunch.

I was hoping for results of a mixed meal of high and low GI foods. Like meat, potato, and a non-starchy veg.

PeachyCarol

yarwell wrote: »

Satiety is addressed in a recent review with many references http://www.sciencedirect.com/science/article/pii/S0924224414002386

Talks more about fibre than GI but links to a paper that digs into it a bit more - http://m.ajcn.nutrition.org/content/76/1/281S.full

I'm still reading the first one, but WOW... a placebo effect on ghrelin... amazing stuff.... back to reading it...

senecarr

GI / GL can change for foods based on coming style and being combined with other foods (fats and fibers slow absorption).
The biggest use of the numbers is for diabetics to figure out their insulin dosing.

kshama2001

Good topic! Can't wait to check out the studies.

Since I'm short on time, will mention that people do eat high glycemic load foods alone, especially after the Fat is Evil craze. I also know Weight Watchers who eat less meat due to it having higher points.:

For me:

1 bagel with butter - not a good meal
1/2 bagel with cream cheese - better
1/2 bagel with cream cheese and salmon - best

PeachyCarol

senecarr wrote: »

GI / GL can change for foods based on coming style and being combined with other foods (fats and fibers slow absorption).
The biggest use of the numbers is for diabetics to figure out their insulin dosing.

There's a lot of noise about it, but when you read the studies on it, they're really cooked to give the results they're expecting.

I'd like to see some studies conducted on meals with mixed high and low food meals.

I've seen the diabetics on the boards talk about the combining, and I have a friend on my FL with insulin resistance who does the same. And then there are other posters who live and die by the GI index.

I was hoping to dig to the bottom of it.

Me? Bring on the potatoes. You should read that first link yarwell posted, there are some cites on fascinating studies in there.

yarwell

http://m.ajcn.nutrition.org/content/47/1/53.abstract and http://m.ajcn.nutrition.org/content/94/4/992.short cover mixed meals, some controversy in followup correspondence. I searched - glycemic index of mixed meals in Google.

My pet hate of GI is the terminology where 55 can be "low". 0-30 31-70 and 71-100+ would be more to my taste for low, medium and high.

PeachyCarol

kshama2001 wrote: »

Good topic! Can't wait to check out the studies.

Since I'm short on time, will mention that people do eat high glycemic load foods alone, especially after the Fat is Evil craze. I also know Weight Watchers who eat less meat due to it having higher points.:

For me:

1 bagel with butter - not a good meal
1/2 bagel with cream cheese - better
1/2 bagel with cream cheese and salmon - best

Bringing in strawman generalized "people" on a board predominantly full of nutrition-conscientious dieters isn't constructive to the discussion.

Anyway, for those "people", they have information they can look up.

For the rest of us, I was wondering if anyone more facile with search terms than I might be able to find some studies on mixed index/load meals.

kshama2001

For those new to the topic.

Carbohydrates and Blood Sugar

...Glycemic index

In the past, carbohydrates were commonly classified as being either “simple” or “complex,” and described as follows:

Simple carbohydrates:

These carbohydrates are composed of sugars (such as fructose and glucose) which have simple chemical structures composed of only one sugar (monosaccharides) or two sugars (disaccharides). Simple carbohydrates are easily and quickly utilized for energy by the body because of their simple chemical structure, often leading to a faster rise in blood sugar and insulin secretion from the pancreas – which can have negative health effects.

Complex carbohydrates:

These carbohydrates have more complex chemical structures, with three or more sugars linked together (known as oligosaccharides and polysaccharides). Many complex carbohydrate foods contain fiber, vitamins and minerals, and they take longer to digest – which means they have less of an immediate impact on blood sugar, causing it to rise more slowly. But other so called complex carbohydrate foods such as white bread and white potatoes contain mostly starch but little fiber or other beneficial nutrients.

Dividing carbohydrates into simple and complex, however, does not account for the effect of carbohydrates on blood sugar and chronic diseases. To explain how different kinds of carbohydrate-rich foods directly affect blood sugar, the glycemic index was developed and is considered a better way of categorizing carbohydrates, especially starchy foods.

...The glycemic index ranks carbohydrates on a scale from 0 to 100 based on how quickly and how much they raise blood sugar levels after eating. Foods with a high glycemic index, like white bread, are rapidly digested and cause substantial fluctuations in blood sugar. Foods with a low glycemic index, like whole oats, are digested more slowly, prompting a more gradual rise in blood sugar.

...Glycemic load

One thing that a food’s glycemic index does not tell us is how much digestible carbohydrate – the total amount of carbohydrates excluding fiber – it delivers. That’s why researchers developed a related way to classify foods that takes into account both the amount of carbohydrate in the food in relation to its impact on blood sugar levels. This measure is called the glycemic load. (11,12) A food’s glycemic load is determined by multiplying its glycemic index by the amount of carbohydrate the food contains. In general, a glycemic load of 20 or more is high, 11 to 19 is medium, and 10 or under is low.

The glycemic load has been used to study whether or not high-glycemic load diets are associated with increased risks for type 2 diabetes risk and cardiac events. In a large meta-analysis of 24 prospective cohort studies, researchers concluded that people who consumed lower-glycemic load diets were at a lower risk of developing type 2 diabetes than those who ate a diet of higher-glycemic load foods. (13) A similar type of meta-analysis concluded that higher-glycemic load diets were also associated with an increased risk for coronary heart disease events. (14)

Here is a listing of low, medium, and high glycemic load foods. For good health, choose foods that have a low or medium glycemic load, and limit foods that have a high glycemic load.

Read more: http://www.hsph.harvard.edu/nutritionsource/carbohydrates/carbohydrates-and-blood-sugar/

PeachyCarol

yarwell wrote: »

http://m.ajcn.nutrition.org/content/47/1/53.abstract and http://m.ajcn.nutrition.org/content/94/4/992.short cover mixed meals, some controversy in followup correspondence. I searched - glycemic index of mixed meals in Google.

My pet hate of GI is the terminology where 55 can be "low". 0-30 31-70 and 71-100+ would be more to my taste for low, medium and high.

Thanks, brewing a cup of lemon herb tea and getting ready to read!

kshama2001

mamapeach910 wrote: »

kshama2001 wrote: »

Good topic! Can't wait to check out the studies.

Since I'm short on time, will mention that people do eat high glycemic load foods alone, especially after the Fat is Evil craze. I also know Weight Watchers who eat less meat due to it having higher points.:

For me:

1 bagel with butter - not a good meal
1/2 bagel with cream cheese - better
1/2 bagel with cream cheese and salmon - best

Bringing in strawman generalized "people" on a board predominantly full of nutrition-conscientious dieters isn't constructive to the discussion.

Anyway, for those "people", they have information they can look up.

Like I said, short on time. More tomorrow!

barbecuesauce

mamapeach910 wrote: »

kshama2001 wrote: »

Good topic! Can't wait to check out the studies.

Since I'm short on time, will mention that people do eat high glycemic load foods alone, especially after the Fat is Evil craze. I also know Weight Watchers who eat less meat due to it having higher points.:

For me:

1 bagel with butter - not a good meal
1/2 bagel with cream cheese - better
1/2 bagel with cream cheese and salmon - best

Bringing in strawman generalized "people" on a board predominantly full of nutrition-conscientious dieters isn't constructive to the discussion.

Anyway, for those "people", they have information they can look up.

For the rest of us, I was wondering if anyone more facile with search terms than I might be able to find some studies on mixed index/load meals.

+1000000000000

I am going to work my way through Yarwell's links now. Very interesting. And as for the OP, I hadn't considered that a combination of high-GI carbs with protein/fiber-filled foods would make a difference. A very filling weeknight meal I do is lean ground meat with chili seasonings, tomatoes, and kidney or pinto beans on top of a baked potato. Keeps me full until bedtime, and I love night time snacking.