Different people need different diets, study finds

Curious as to why that diet that helped your friend lose 50 pounds and did next to nothing for you? The answer may lie in the way that your body metabolizes different types of food, according to new research touting the importance of personalized nutritional programs.
The study, led by Eran Segal and Eran Elinav of the Weizmann Institute of Science in Israel and published in Thursday’s edition of the journal Cell, tracked the blood sugar levels of 800 patients over the span of one week to see how each person’s body would metabolize the same meals.
Blood sugar was chosen because of its association with conditions such as obesity and diabetes, the researchers explained. They found that the glycemic index (GI), the metric used to rank food based on how they affect blood sugar levels, is not a fixed value, but that it varies by person.
The high variability in response to identical meals suggests that universal dietary guidelines may not be as useful as previously believed, the authors said. Different people had different responses to identical meals, and those individual responses remained consistent from day to day.
Personalized diets could help control blood sugar levels
Segal, Elinav, and their colleagues collected data from each participant in the form of health-related surveys, body measurements, blood tests, glucose monitoring, and stool samples, as well as activity and food intake data (as provided by a mobile app). Nearly 47,000 total meals were measured—including some standardized breakfasts provided to volunteers.
The authors found a link between post-meal blood glucose levels and both age and body mass index (BMI), as well as the varied responses to the same types of foods. Next, the research team devised a machine-learning algorithm based on a variety of factors (including dietary habits and physical activity levels) that could accurately predict post-meal biological responses.
While most dietary recommendations are based on universally applied grading systems, Segal said, “there are profound differences between individuals” that are often overlooked. “In some cases,” he said, “individuals have opposite response to one another, and this is really a big hole in the literature.”
The findings “really enlightened us on how inaccurate we all were about one of the most basic concepts of our existence, which is what we eat and how we integrate nutrition into our daily life,” added Elinav. “In contrast to our current practices, tailoring diets to the individual may allow us to utilize nutrition as means of controlling elevated blood sugar levels and its associated medical conditions.”
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