Same drink. Two versions.

I bought two cans last week. One classic Coke. One Coke Zero. Same fridge. Same week. Same me.

I wore my glucose monitor for both.

The results were not close.

I'd guessed the direction before I even opened the fridge. Regular Coke was always going to win the spike. But I didn't expect the gap to be quite this wide.

A can of regular Coke has about 39 grams of sugar. In other words, almost ten teaspoons, poured straight into a glass. Half of that sugar is glucose, which hits your bloodstream fast. The other half is fructose, and your liver has to process that part first.

My blood sugar rose about 76 points after that can.

It climbed fast. It peaked around the half hour mark. Then it dropped hard.

That drop matters too. When blood sugar falls quickly after a big rise, you can end up hungry again within the hour. It's a rough cycle.

Now the Coke Zero.

Same size can. Same fizz. Zero sugar, because it swaps sugar for aspartame and acesulfame potassium instead.

My blood sugar barely moved. It rose about 9 points, then settled back down within twenty minutes.

On paper, Coke Zero looks like the easy winner. And for blood sugar in that moment, it is.

But here's the thing researchers keep circling back to.

● The Science

A recent study using continuous glucose monitors tested this same swap in 66 healthy adults. Regular cola caused a fast rise and a sharp drop, just like mine did. Coke Zero stayed nearly flat, close to water. So far, that matches what my own arm showed.

But the researchers found something else too. A group within that study, about a quarter of the people, had blood sugar that reacted more, not less, when they drank Coke Zero with food, compared to drinking regular cola with the same meal. Nobody fully understands why yet.

My wife thinks I'm a little insane for testing all this on myself with a sensor taped to my arm. She's probably right. But I'd rather know than guess.

And a review published by Tufts University researchers this July looked back across 21 separate studies on artificial sweeteners. In other words, this isn't one lab and one surprising result. It's a pattern showing up again and again. The researchers found these sweeteners can raise fasting insulin and a longer-term blood sugar marker called A1C, likely by changing the bacteria living in your gut.

That matters beyond just soda. So much of the current conversation around weight and blood sugar circles back to GLP-1 drugs like Ozempic, and to the question of whether food choices can do part of that job on their own. Zero-sugar drinks get pitched as an easy piece of that puzzle. This research suggests the puzzle has more pieces than the marketing lets on.

I don't think that means panic and pour the Coke Zero down the drain. The research is early, and it's mostly looking at heavy, daily use over years, not one can on a hot afternoon.

It's not the dramatic story the headlines want. It's messier than that.

So where does that leave you? Zero-calorie soda still wins for your blood sugar today. But the idea that it does nothing to your body, ever, looks wrong.

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

● The Hack: If You Must

So what if you still want the real thing sometimes? I get it. Coke was basically a food group for me in my twenties. My kids still ask for it at birthday parties, and I'm not about to make soda the villain of every conversation. Here's how to have it without making things worse.

● By The Way

Coke isn't the only drink playing this game. A few other "better for you" options spike about as hard once you check what's inside the can or bottle.

Read the can, not just the label's marketing. A lot of drinks wearing a health claim spike about as hard as the soda they're supposed to replace.

So here's where I've landed, at least for now. I still keep Coke Zero in the fridge. I still have a real Coke now and then, usually with dinner, never on an empty stomach. Small choices, not big ones. That's most of what this newsletter is about anyway.

Stay steady