It may have something to do with what you ate — or didn’t eat. A meal without much fiber or protein won’t keep you full for long. Protein takes longer to digest than carbohydrates, and fiber helps slow the digestive process — all of which helps keep you feeling sated. Fast-burning, low-fiber carbohydrates, such as white bread, pasta, and pizza, won’t keep you feeling full.
Protein also reduces ghrelin levels and increases leptin sensitivity. “Protein is an incredibly satiating macronutrient,” Wohl says.
Similarly, a meal containing a lot of sugar (think French toast with syrup and a large cup of sweetened coffee) can set off an insulin reaction that leaves you feeling not just hungry but cranky. You might then crave protein or fat, a sign that your body is struggling to get macronutrients that can satisfy it. (To learn more about how excess insulin can provoke hunger, see “Hungry No More.”)
Finally, you may just need water. “Sometimes when people think they’re hungry . . . they’re actually thirsty,” notes Lipman.