There's a Scientific Reason Your Friends Are Losing Weight But You're Not

So don't feel bad.

Do you have that friend who genuinely feels refreshed and energetic after a juice cleanse? If you hate that friend, take heart: science is here to explain why they make you feel horrible. The Washington Post reports (opens in new tab) that a new study finds different people can react in wildly different ways to the same diet. 

The study, published in the journal Cell (opens in new tab), measured 800 healthy people's blood glucose levels throughout a one-week period using a special device. They also had participants track their diet, exercise, and sleep every day. The participants behaved normally, but they all ate the exact same breakfast, which had 50 grams of carbohydrates. The idea was to check how blood glucose spikes after eating food, since high levels can be linked to obesity, diabetes, and heart disease.

The researchers, who are from the Weizmann Institute of Science (opens in new tab) in Israel, found that even when people ate the exact same foods, they processed those nutrients in different ways. Sure, age and body mass index had an effect on the results, but other than that, people had extremely different glucose levels after eating the same thing. This led the researchers to conclude that there are a number of factors, like your gut bacteria, dietary habits, and physical activity, that determine how you break down the food you eat. 

What's the solution? The researchers say personalization is key, and tailor-made diets might be the new paleo. They came up with an algorithm to predict how a person will react to food based on their lifestyle, health panel, and gut microbiomes, and then they designed a personalized diet based on that algorithm. The Post points out that one woman in the study saw her blood sugar spike after she ate tomatoes, so she had a personalized diet that nixed tomatoes. In a group of 100 volunteers, the personalized diets helped keep blood sugar steady and changed the gut microbiome.

So although it's not easy to get a computer-analyzed diet on your own, the research might lead to that in the future. Until then, if you can't seem to lose weight, talk to a doctor or dietician to figure out the best diet for you.

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Megan Friedman
Megan Friedman

Megan Friedman is the former managing editor of the Newsroom at Hearst. She's worked at NBC and Time, and is a graduate of Northwestern's Medill School of Journalism.