Last Tuesday, 8 am.

I ordered the green one.

Spinach, kale, mango, banana, apple juice, and a scoop of powder the menu called "greens." The board named the drink Detox Glow. It cost nine dollars.

Then I sat in my car and watched my glucose monitor. That's the small sensor I wear on the back of my arm. It reads my blood sugar every few minutes and sends the number to my phone.

Forty five minutes later… the Detox Glow had raised my blood sugar about 72 points.

A can of Coke does roughly the same thing to me.

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

Here's the thing. I expected the opposite, because the research had been telling me smoothies were fine.

The internet has been arguing about this all year. One side says blending fruit breaks up its fiber and lets the sugar reach your blood faster. Jessie Inchauspé, who writes as the Glucose Goddess, tells millions of readers to skip smoothies for that reason.

But the studies don't back that up.

In May, a food fact-checking group put the claim to Dr Nicola Guess, a diabetes researcher. Her answer was plain. Blending fruit instead of eating it whole doesn't necessarily raise your blood sugar more, and some studies show that blending raises it less.

Less. Not more.

A 2022 trial blended apples and blackberries together and measured a smaller rise in blood sugar than eating the same fruit whole. A 2020 study on raspberries and passion fruit found the same pattern. Researchers at the University of Plymouth think the crushed seeds are doing the work. Blending grinds them up, which releases fiber and fat into the drink, and both of those slow sugar down.

So if the blender isn't the problem, what raised my blood sugar 72 points?

The ingredient list.

My Detox Glow was mostly apple juice, mango and banana. In other words, it was a fruit-sugar drink with a handful of spinach in it. The spinach was real. There just wasn't much of it.

The Plymouth team flagged this themselves. Their fruit was blended with water, and they wrote that their results shouldn't be stretched to cover shop smoothies, which usually start with apple juice, sorbet or ice cream.

That gap between the study and the cup in my hand is the whole story.

● Meanwhile… The Hack

So on Thursday I made one at home.

I kept the spinach. Everything else changed. Frozen berries instead of mango and banana. Half an avocado. A big spoon of plain Greek yogurt. A teaspoon of chia seeds. Unsweetened almond milk instead of apple juice.

Twenty two points.

It was still cold, still green, still breakfast. And my morning didn't end in the slump I usually get around eleven.

Why does that work? Protein, fat and fiber all slow down how fast your body absorbs sugar from a meal. In other words, the same sugar still arrives, it just arrives over two hours instead of twenty minutes. One small trial found that adding yogurt to a smoothie lowered the rise in blood sugar by about 15%.

Here's how I build one now.

My wife makes hers with the kids' frozen berries and says it beats the nine-dollar version. She might be right.

I don't know if a rebuilt smoothie will do the same for you. The research on blended fruit is still young, and people vary more than any study average shows. But the direction looks steady enough to try one morning.

● The Bigger Picture

By the way, my Detox Glow wasn't the worst thing on that counter.

Every one of those has a health story printed on the front. None of the stories say what the drink does to your blood sugar.

We don't have to give up smoothies. We just have to read past the color.

Tomorrow I'll show you the smoothie formula I use, and what happens when you get the order of ingredients wrong.

Stay steady