My wife made a face.

I'd swapped our baked potato for a baked sweet potato. She said it was the healthier pick... lower blood sugar, she said. I wasn't so sure.

So I put on my glucose monitor and tested both. Same size potato. Same oven, same forty minutes at four hundred degrees. Two nights apart, with nothing else in the meal different.

The sweet potato lost.

That surprised me too.

Sweet potatoes carry a reputation as the gentle carb, the one you're allowed to eat without guilt. But baking does something specific to starch. The heat unwinds it into a form your body absorbs fast, and it does that to any potato, orange or white.

In other words, the color inside the potato has nothing to do with how fast it hits your blood sugar. The cooking method does.

A baked Russet potato runs a glycemic index around 85, according to the University of Sydney's glycemic index database. A baked sweet potato runs even higher, close to 94. That's not a typo, and it's not marketing copy either.

So baked isn't the gentle choice for either one.

Boil the same two potatoes, though, and the whole story flips.

A boiled white potato sits around a glycemic index of 56. A boiled sweet potato drops even lower, down near 44. That's near the bottom of the entire scale, lower than a lot of fruit.

My own numbers backed it up. The boiled sweet potato barely moved my blood sugar. The boiled white potato moved it more, but nowhere close to what either one did baked.

This is one person's experiment, not medical advice. Everyone's body responds differently.

It's revealing.

The potato you pick matters less than what you do to it. A cooking method, not a vegetable, decides whether your blood sugar climbs fast or slow.

And that's the real story behind something that's been getting attention lately. A review published a couple weeks ago made the same point about potatoes in general: a food can be low in sugar and still carry a high glycemic impact. Sugar content and blood sugar response are two completely different measurements. One tells you how sweet something tastes. The other tells you how fast it raises your blood sugar.

There's a bigger study behind that too. Researchers tracked more than 200,000 people for close to forty years and found something specific: eating fries three times a week raised the risk of type 2 diabetes by 20 percent. Baked, boiled, and mashed potatoes, though, showed no meaningful link at all.

So the frying oil may be doing more damage than the potato ever does.

None of this makes fries evil or bans them forever. It just means the cooking method carries more weight than whatever label is on the bag.