Potatoes and the Glycemic Index

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The Glycemic Index is all the rage right now. I am a big fan, but I have a few hints that might vary from what you read in most places.

The Glycemic Index is a measure of a food’s ability to spike your blood sugar. The index goes from 0 – 100+. (Yes, a food can actually score higher than 100. And white sugar is 100 so you know that’s sweet).

I consider any food that scores a GI of 50 or less as healthy (for diet purposes).

The Glycemic Index is more popular in New Zealand and Australia than in the US. They even mention a food’s GI score in TV commercials or on the boxes of things like cereal.

As with most things in America, we cut Big Food too much slack in my opinion. Instead of deeming things that score 50 or less as healthy, in America most listings will score foods as low, medium and high. 50 – 70 is considered medium. 70+ is high and not recommended or at least eat very little of it and keep it for special occasions.

So, let’s talk potatoes and the Glycemic Index.

Rule of thumb is the smaller (or younger) a potato is the lower the GI (Glycemic Index). Potatoes like fingerlings or small red potatoes (also called C-size) will have a lower GI. So just look for the smallest potatoes offered at your local store.

Larger potatoes have a higher starch content and therefore a higher GI. They all score high. And how you cook them matters. Believe it or not, a microwaved russet potato scores a whopping GI of 124! In the old days I used to come home from work and microwave a small russet and put diet margarine on it. I did that because they were low calorie. I was eating a 150 calorie dinner and thought I was doing myself a favor. No wonder I kept getting fatter! I had no clue.

The only large potato exception is a sweet potato but how you cook potatoes matters. A boiled sweet potato will score a GI of 44. That’s good. A baked sweet potato launches to 94. Not good. You now have something that resembles candy.

Mashing your potatoes and making them fluffy can skyrocket the Glycemic Index by as much as 25%. Boiled, baked or mashed white potatoes will always score high.

Adding oil helps. That’s why French fries and potato chips have a lower GI than, let’s say, a baked potato. French fries score 75. That doesn’t make them “good for you.” Don’t fool yourself. But if you’re like me and you cut yourself off at 4 or 5 fries rather than eating the whole pile, they can be part of your diet; just not every day.

Adding fat helps. Real butter not diet margarine. Cheese helps, too — even sour cream and bacon bits. Anything with fat slows down the Glycemic Load. Glycemic Load or GL is the rate at which the spiking of blood sugar ensues.

The way to have the lowest score in the GI or GL categories is to make the potatoes ahead and chill them until they are completely cold. Then you can heat them back up and have a low(er) GI/GL experience.

What happens is some of the starches in the potatoes become what is called resistant carbs. Basically, this process causes the potatoes to digest slower, so they digest slower in your system and don’t cause the same blood sugar spike.

So, as often as possible plan your potatoes a day ahead. This is perfect for cooking for dinner parties or holiday celebrations. One less thing to have to deal with on the day of. All you have to do is re-heat. Potato casseroles often taste even better on day 2 so, this is a bonus.

Enjoy potatoes in moderation and use these hints to make healthier choices.


Dauphinoise Potatoes

Don’t let the name intimidate you. This is a wonderful potato casserole!