Satiety describes the feeling of being full after a meal and of having no need for more food for a certain time. It depends on several factors, such as the volume of a meal, its fibre content and its composition of carbohydrates, fat and protein. In nutrition science, protein is often regarded as the nutrient with the strongest satiating effect per calorie. The consistency of a meal also plays a role: solid, bulky foods often satisfy differently from drinks with a similar energy content.
In practice, a meal richer in protein can help you feel less hungry over a longer period, for example when low-fat quark, legumes, fish or poultry are part of the meal. How strong this effect is varies from person to person and also depends on the meal as a whole, not on the protein content alone. If you want to pay specific attention to satiety, you can deliberately add a protein-rich component to meals instead of focusing only on the calorie count.
Satiety is often discussed in connection with weight loss, and an overview can be found in the guide Protein for weight loss. More on the related topic of energy use during digestion is explained in the entry Thermic effect.