Take a slice of cake and cut it in two. Eat one half, and let a friend scoff the other. Your blood-sugar levels will both spike, but to different degrees depending on your genes, the bacteria in your gut, what you recently ate, how recently or intensely you exercised, and more. The spikes, formally known as “postprandial glycemic responses” or PPGR, are hard to forecast since two people might react very differently to exactly the same food.
But Eran Elinav and Eran Segal from the Weizmann Institute of Science have developed a way of embracing that variability. By comprehensively monitoring the blood sugar, diets, and other traits of 800 people, they built an algorithm that can accurately predict how a person’s blood-sugar levels will spike after eating any given meal.
Many of the diets created by the algorithm were deeply unorthodox. “It wasn’t just salad every day,” says Segal. “Some people got alcohol, chocolate, and ice-cream, in moderation. These are items that you’d typically never find on a dietician’s recommendations.” Some plans were so counter-intuitive that neither dieticians nor volunteers could tell whether they were meant to represent the good diet or the bad one. And yet, they effectively controlled blood-sugar levels for those particular volunteers.