Turns out that one person's salad is another person's cheeseburger.
Ever tried a diet that worked miracles for your friend, only to attempt it for yourself and see your weight go up? It's frustrating as all get out, but the reason this happens is both as obvious and complex as the human body itself. Because every body is genetically different, every body responds to different foods in unique ways. That means—spoiler alert—there's no one-size-fits-all diet.
Nutritionists might have been saying this for years, but science has finally proven the theory of bio individuality correct: Researchers from Israel published a study in Cell outlining the results of their 800-person study on glycemic index, blood sugar, and weight.
After studying biological responses to 46,898 meals, the team discovered that when subjects ate the exact same meals their blood glucose levels were highly variable. Even diets that were specifically created to keep blood glucose levels lower and more balanced had varying effects depending on the participant. One typical "healthy food," like a tomato, could affect one person's blood sugar as expected by keeping it more balanced, but could cause a rapid spike in another's blood sugar, indicating that it's an "unhealthy" food for that individual.
If identical foods cause totally different biological responses in people, it makes sense that a particular trend diet could work for your friend but not for you. The same goes for people who seem to eat unhealthy foods but never gain weight—perhaps their bodies see ice cream as more bioavailable than a green juice. Jealous.
Researchers tested this theory, too. They created distinctive "good" diets for each participant based off of the data gathered—these diets consisted of foods that didn't radically affect the participants' blood sugar levels, as more even blood sugar levels correlate to fat and weight loss. Interestingly, some typically taboo foods like ice cream, alcohol, and even chocolate were allowed as part of healthy diets for some people.
As soon as their new diets began, researchers noticed that the gut microbiota changed in a similar way for many of the people in the study. Certain healthy gut bacteria flourished, while gut bacteria associated with diseases like type 2 diabetes decrease significantly. This indicates that their overall health actually improved as well, beyond just evening out blood sugar levels.
The results of the study are definitely interesting, and it's clear that sweeping dietary recommendations aren't beneficial or useful for most of us. As of right now, the study can't exactly be translated to the average person unless they're willing to test their blood sugar levels with every meal to find their own ideal diet. As the research team continues to improve its algorithm that determines an individual's ultimate healthy diet, we can all look forward to finding customized diets—backed by science—that help us to feel and perform at our best.
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