If you eat a snack—a meatball, say, or a marshmallow—how will it affect your blood sugar? It’s a surprisingly tricky question; the body’s glycemic response to different foods varies based on individual genetics, microbiomes, hormonal fluctuations, and more. Because of that, providing personalized nutritional advice—which can help patients manage diabetes, obesity, and cardiovascular diseases, among other conditions—requires costly and intrusive testing, making it hard to deliver effective care at scale.