I wore a blood glucose monitor and logged food for 10 days, and learned my body prefers fats over sugar

After I reported on a 2019 study that showed how everyone responds a little differently to common foods, I learned the same researchers were setting up another study, aimed at observing how different people's bodies process sugars and fats in different ways. I volunteered for it.

The study authors wanted to explore whether they might be able to use that information to better tailor individual diet recommendations in order to reduce a person's odds of developing chronic diseases, like heart disease or Type 2 diabetes.

The company, called Zoe, enrolled me in Predict 2 in the fall of 2019, shortly before the COVID-19 pandemic began.

The monitor stayed on my arm throughout the entire 10-day study.

I was allowed to shower with it on, or swim for up to 30 minutes, but was advised not to participate in contact sports, and to be careful when putting on a backpack.

The blue shaded area of this graph is the place you want your blood sugar reading to be.

A blood sugar reading below 70mg/dL signals low blood sugar, which can make you faint, weak, shaky, and hungry.

"I wish every citizen in the world could put one of those on," Dr. Mark Cucuzella, a Professor at West Virginia University School of Medicine and healthy eating advocate (who was not involved with this study), said.

"Just to see what is going on."

Every single ingredient in my omelette had to be accounted for.

This painstaking attention to detail made me not want to cook, and I felt a little guilty when I eyeballed or approximated foods I ate instead.

The card was designed to give Zoe researchers a better idea of how big my portion sizes were, and the color scheme of what I ate.

Food color isn't necessarily an indication of nutritional value, but the phytochemicals that give fruits and vegetables their bright colors, odors, and flavors are great at reducing inflammation in the body, which can lead to chronic disease if left unchecked.

Pret a Manger was my go-to lunch pal during this study, because I could just screenshot the ingredient list and nutrition facts of what I ate into the app.

"I know Americans love muffins for breakfast," Spector told me previously.

Three kinds of muffins were on his menu: a high-fat, low-sugar muffin; a standard muffin with an average amount of fat and carbohydrates; and a third low fat muffin that had more sugar in it. The dry, low fat muffin was by far the least appetizing, but none of them were great.

I had to remind myself this wasn't a taste test. The researchers wanted to know: Would my insulin levels spike after the muffins, or would the glucose monitor reflect a fairly stable response? Which of the muffins would sit with me best?

I was instructed to finish eating within 15 minutes.

The glucose drink, if we can call it that, was more like a thick elixir. It tasted like Gatorade with extra simple syrup added in. I was also ordered to drink it fast.

The exact same beverage is used clinically to test people for diabetes.

I watched my blood sugar levels plunge in the hours after the breakfasts.

"A monitor can be a really good teaching tool for patients," Cucuzella said. "I like using it in the clinic."

Saliva spit tests vary in accuracy, but there's some early evidence that suggests they may provide some insights into how your body regulates glucose and other metabolic measures.

The stool sample was used for a gut microbiome test, to see what kinds of bacteria are circulating in my digestive system.

Specter's own research suggests that a relatively rapid "gut transit time" is linked to better microbiome health. But I discovered it's not always terribly obvious when the muffin ... reaches the other end.

"The continuous monitor gives you awareness," Cucuzella said.

He used one on himself and noticed his blood sugar spiking after he ate fruits like melon.

"Get rid of processed food and eat the natural foods — and if you're better in glucose tolerance, you can have more fruit," he said.

After roughly three decades of consuming an American diet ripe with sugary sweet foods and drinks, it's not a huge surprise. But it was a good reminder to take better care of myself, and my diet. I'll skip the dessert, thanks.

"Any kind of program like this that gives you some insight ... will make you make better life choices, with real food," Cucuzella said.

For example, a bowl of fatty, fibrous oatmeal is likely a better breakfast choice for me than a piece of fruit.

A picnic of hard boiled eggs and spinach salad with some garlic bread got high ratings from the Zoe team.

"A doughnut is not a food," Cucuzella said. "If you want to have a healthy gut, healthy bugs in the gut, you've got to feed them fiber and natural plants."

The basic truths that have underlined decades of scientific research about nutrition held true in my own study: whole foods like plants and animal products are good for you, while sugary processed foods are not.

It wasn't a revelation, but it's certainly consistent with the body of research that's out there.

Processed foods and meats are linked to all kinds of poor health outcomes, including early death, so the advice isn't controversial among nutrition experts.

"There's a lot of fancy tools to tell us what's inherently obvious: Don't eat food that your grandmother wouldn't recognize as food," Cucuzella said.