The drop in a person’s blood-sugar levels a few hours after a meal predicts how much they’ll eat over the rest of the day, suggesting that hunger can be quantified.
Ana Valdes at the University of Nottingham, UK, and her colleagues followed the eating habits of 1,070 healthy adults in the United Kingdom and United States for 2 weeks. Study participants ate a set breakfast and then fasted for 3 hours, after which they ate as they chose. They wore sensors that continuously monitored their blood sugar levels and activity, and logged their meals and hunger levels in a mobile phone app.
Across the group, the drop in blood sugar levels 2–3 hours after breakfast corresponded with the size of the meals that participants ate over the next 24 hours, and matched their reported hunger levels. The authors say that the study, the largest of its kind, provides the best evidence yet that blood-sugar dips could be a possible biomarker for appetite.
However, the dips are just one part of the picture, they add, because appetite is known to be influenced by social, psychological and other factors.