Whey is a hormonal appetite suppressant
If you become obsessed with the constant appetite for food during weight loss attempts, try incorporating whey protein shakes into your diet. This will decrease your appetite for food, while at the same time increasing the chance that you will actually lose those excess pounds. This is shown in a human study by researchers at the University of Milan.Study
On 2 different occasions, the researchers gave 8 young and obese women a shake. One time this shake contained 43 grams of maltodextrin, the other time 45 grams of whey. The researchers used a whey isolate from the Italian supplement manufacturer Enervit.

After the subjects drank a shake with whey, their feeling of hunger decreased more, and the feeling of satiety increased more, than after the women drank a shake with maltodextrin.

Whey led to a higher rise in the level of the satiety hormone GLP-1 in the blood than maltodextrin. Whey had the same effect on PYY, another satiety hormone, but this effect was less pronounced.

The shake with whey caused a significant increase in the amount of amino acids in the blood [TAA in the figures below].

The researchers then looked at the amino acids separately in the subjects' blood. They found that the amino acids isoleucine, leucine, lysine, methionine, phenylalanine, proline, tyrosine and valine correlated with a decrease in the feeling of hunger, an increase in the feeling of satiety and an increase in the GLP-1 level. The Italians suspect that these amino acids stimulate receptors in the L-cells in the small intestine.Conclusion
"Eight specific amino acids (isoleucine, leucine, lysine, methionine, phenylalanine, proline, tyrosine, and valine) are implied in the appetite-suppressant and GLP-1-stimulating effects of whey proteins, which may be mediated by their binding with nutrient-sensing receptors expressed by L-cells within the gastrointestinal wall", the Italians write.

"The long-term satiating effect of whey proteins and the effectiveness of a supplement with these amino acids (i.e., as a nutraceutical intervention) administered during a body weight reduction programs might deserve to be investigated in future studies."
Nutrients 2020;12(3):775.