Whey satisfies best, study finds

Protein is generally agreed to have the biggest impact on satiety, the feeling of fullness after a meal. But different protein sources have different effects on satiety, as recent research has found.

Scientists at the University of Surrey, England, put casein and whey to the test – the two most common dairy protein sources used in protein powder. They measured the effects of each on food intake, feelings of hunger and fullness, and on metabolic and hormonal responses.

They first looked at how much food was eaten in the period after a casein or whey drink was consumed. The drinks had equivalent caloric and nutrient value, but with either 48g whey or 48g casein. After 90 minutes, participants ate foods of their choice from a buffet selection. The whey group ate significantly less compared to the casein group.
 
In a second test, researchers found that blood concentration of amino acids over a three hour period after consumption was 28 percent higher in the whey group compared to casein. Concentration of cholecystokinin (CCK, the chemical messenger signalling satiety), was 60 percent higher after whey, and glucagon, the fat-burning hormone, was also higher, with glucagon-like peptide concentration 65 percent up on casein.

When asked about feelings of fullness, the subjects reported greater satisfaction after the whey than with casein.

Aussie Bodies nutritionist Leigh Blashki said the type of food source was just one piece of the puzzle in understanding satiety.

"There are so many variables when it comes to satiety, as science is still investigating. The feeding time, whether you chew or drink a meal, how 'bulky' the food texture is, caloric density and of course the PCF of the meal can all have an impact," he said.

"What we do know is that protein foods generally rate higher for satiety than other nutrients and seem to stimulate more CCK.

"While whey may be more satisfying than casein, it's important to bear in mind that both have the same PDCAAS rating for useability and digestibility (1.0). Furthermore calcium caseinate, as found in many protein-enriched products, is absorbed more slowly which can be useful for sustaining round-the-clock muscle support."