In general, protein is the more satiating than either carbohydrates or fats. It turns out that certain proteins are more satisfying than other proteins.
Study participants that consumed either alpha-lactalbumin or gelatin at breakfast consumed 20% fewer calories at lunch compared to those consuming casein, soy, or whey at breakfast. Appetite ratings 3 hours after breakfast showed a 40% greater satiation for the groups that consumed either alpha-lactalbumin or gelatin at breakfast.
Gelatin is derived from collagen… the most common protein in the human body. The best sources of gelatin are broths from cooking animal bones and skin (e.g. homemade chicken soup). Sugar free Jello products are also a decent source.
Alpha-lactalbumin is found in milk and whey proteins. It is also the primary protein found in human breast milk, which contains 4 times more than cows milk.