woman on scale holding donut in one hand and apple in the other woman on scale holding donut in one hand and apple in the other It's so hard to choose, isn't it? But with a personalized diet, it might be a lot easier. (Photo: Yuriy Maksymiv/Shutterstock)

Diets are getting very personal, and a new book explains why

The authors say eating according to your body's blood sugar is the best way to control weight.

One man's white bread is another man's leafy green.

That's the key takeaway from "The Personalized Diet," a new book from Israeli authors Eran Segal and Eran Elinav, professors at the Weizmann Institute of Science in Israel. Calling it a "pioneering program" for weight loss, the authors say it's time to admit to ourselves that one-size-fits-all diets don't work, and when it comes to nutrition, it's about doing what works best for your body, not catching the latest fad diet wave.

"For years, we've been trying to search for that silver-bullet diet that would work for everybody and we've been miserably failing,” Segal told ABC News. “And that's because the best diet for each person really has to be tailored to that individual.”

Woman choosing between healthy and unhealthy meal. Nutrition just got very personal. (Photo: IAKOBCHUK VIACHESLAV / Shutterstock)

The two Erans have been studying this phenomenon for years, experimenting with certain foods and seeing how people respond. They also studied whether eating at certain times of the day causes more weight gain – the proverbial "midnight snack," for instance. And, in 2015, Elinav reported in a study that artificial sweeteners are more harmful than once thought, urging people to choose natural alternatives like dates and maple syrup instead.

dates on a cutting board Dates are a sensible answer to sugar overload. They're also great in recipes. (Photo: Igor Normann / Shutterstock)

They conducted a Personalized Nutrition Project at Weizmann, where hundreds of volunteers agreed to have their blood sugar tested after meals. One participant in the study, a woman named Ruti, said she was surprised that it was tomatoes – not ice cream, or brownies, or sugary sodas – that were spiking her blood sugar.

Colorful assortment of fruit You can't always rely on conventional science to guide your eating habits. (Photo: Africa Studio / Shutterstock)

"I sat down with one of the study coordinators after the study was over, and he showed me that in all my meals that included tomatoes, I had these obvious glucose spikes!" Ruti recalled. "I have now significantly reduced my tomato intake and I’m feeling much more energetic, which still surprises me. I have already lost a couple of pounds, and I have high hopes that I have finally found the answer to my weight struggle, too."

Segal gave a TED Talk on the topic in 2016, urging people to question their own long-held beliefs about dieting.


By using blood sugar as a barometer, the Israeli scientists found that some people can consume traditionally unhealthy foods with little to no blood sugar spike, while others have a stronger response, and therefore shouldn't eat those foods. It's those kinds of results that you can only find from a personalized diet, Segal and Elinav said.

diabetes test Pricking your finger after every meal might not be pleasant, but Elinav and Segal said it's the only way to determine the best diet for your body. (Photo: Image Point FR / Shutterstock)

"What we were surprised to find out was just like any other food, there is no such thing as a good bread,” Elinav said. “The response to bread was completely individualized.”

Their book, "The Personalized Diet," is now available.

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Diets are getting very personal, and a new book explains why
The authors say eating according to your body's blood sugar is the best way to control weight.