Summary (All Essential Benefits/Effects/Facts & Information)

Whey protein is one of the two proteins found in Milk, with the other being casein. When a coagulant (usually renin) is added to milk, the curds and the wheys form (solid and liquids) with the curds being casein and the wheys being whey. Whey protein is the water-soluble portion of milk, and is comprised of various water-soluble amino acids and protein structures as well as anything else lost in this portion.

Although many benefits associated with Whey protein are due to it being a protein itself (and thus could be extended to many protein sources), Whey appears unique in the sense that it delivers a large amount of the amino acid L-Cysteine. A subclinical deficiency state of L-Cysteine may exist during aging and diabetes (as well as some other conditions) that can be alleviated with additional dietary L-Cysteine; either a surplus of protein in general or more efficiently through Whey protein due to more Cysteine per gram of protein.

Whey is touted at being faster absorbed than other forms of protein, and this is demonstrably true. However, this increased speed does not seem to transfer well to increased Muscle Protein Synthesis when the body is already in a fed state. Whey may be better than other protein sources at inducing protein synthesis in a fasted state (first meal of the day), but does not seem to be significantly better when protein is added to a long-term exercise regimen. Beyond breaking a fasted state, preferably when exercise was also done, the increased speed of whey protein does not appear to confer much practical benefit (despite theoretically being able to).

Whey is also touted to increase fat loss, but this appears to be a function of protein per se rather than whey and is not like a classical fat loss agent (Whey can make fat loss go more smoothly, but does not inherently reduce fat; requiring a caloric deficit). The efficiency aspect of whey does play a role, with Whey being a better protein choice for preservingLean Mass and reducing Fat Mass for people who are either not consuming enough protein at the onset or persons who are barely consuming enough (usually 0.8-1.2g/kg Lean Mass; total mass minus Fat Mass). At higher protein intakes, other sources such as soy seem equally effective as whey at aiding in a fat loss regimen.

Like all other protein sources, whey does not inherently harm the liver or kidneys, but it can exacerbate pre-existing damage. Persons with harmed livers or kidneys (disease states or otherwise) should exercise caution in increasing protein intake too quickly and without the guidance of a medical doctor.