Which protein burns more fat: whey or casein?

Protein is known to promote greater satiety and increase energy expenditure better than carbohydrates, but few controlled studies have examined the differences between protein sources. To address this void, a recent highly controlled study used a respiratory chamber, which allows detailed measures of energy expenditure and fat oxidation, to test the differences between whey and casein proteins.

Twenty-four obese individuals spent 24-hours in a respiratory chamber on three separate occasions. During one trial they consumed intact whey protein (30g) 3-times per day as part of a mixed meal. During the other two trials they were provided an equal amount of intact casein or hydrolyzed casein. Casein is a slow-digesting protein in milk that is best known as the protein in cheese or cottage cheese.

The studies revealed that there was no difference in 24-hr energy expenditure or appetite ratings between the trials. However, whey consumption was associated with a greater energy expenditure from fat compared to casein. Nearly 52% of the energy expenditure was derived from fat when taking whey, compared to 45% for hydrolyzed casein and 48% for intact casein. The greater fat oxidation after whey consumption was supported by increased concentrations of fatty acids in the blood, indicating greater fat breakdown. This well-controlled study using state-of-the-art technologies for measuring energy expenditure indicates that repeated intake of whey protein promotes greater fat oxidation (burning) compared to casein.


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