One of the reasons I focus so much on dietary carbohydrates is that no nutrient in the blood is as volatile as glucose. It can climb sharply within minutes of a meal and fall just as quickly. And as much as the blood sugar spike after a meal gets most of the attention, when it comes to hunger, the drop that follows may matter more.
In a study of more than a thousand people wearing continuous glucose monitors, researchers looked at what happened to blood sugar in the hours after eating and how hungry people felt afterward. The size of the spike wasn't the best predictor of hunger. The dip was.
Some people's glucose rose after a meal and then settled back to where it started. Others rose and then fell below their starting level about two to three hours later. That second group, the "big dippers," got hungrier sooner, ate their next meal earlier, and took in more calories over the rest of the day.
This helps explain a common experience. Someone eats a breakfast of cereal, toast, or a pastry, feels fine for a while, and then by mid-morning is hungry again and looking for a snack. It isn't a lack of willpower. Their blood sugar went up quickly and then came down below where it began, and the body responds to that drop by pushing them to eat.
It also shows why the same meal can affect people so differently. One person's glucose barely dips after a bowl of oatmeal, while another's crashes. This is one more reason a glucose monitor is so useful. It shows not only how high a meal sends your glucose, but how far it falls afterward.
Meals built around protein and fat, with fewer refined carbohydrates, tend to produce a smaller rise and a gentler return, which means less of a dip and steadier hunger.
If someone keeps feeling hungry a couple of hours after eating, it's worth looking at whether that meal is sending their blood sugar up and then down below where it started.