The Effect of Hydrolyzed Casein on Energy Expenditure and Subjective Appetite

The primary aim is to examine and compare the effects of hydrolyzed casein (HC), intact casein (IC) and intact whey protein (IWP) on diet-induced thermogenesis (DIT). Furthermore, to study the effects on appetite regulation assessed by subjective appetite sensations, ad libitum energy intake and appetite regulating hormones.

Whey and casein differ in absorption and digestion rate, with whey being a fast protein and casein being a slow protein. When casein undergoes hydrolysis the absorption and digestion rates approaches the rates of whey. In the present study the importance of absorption rate and amino acid composition, in regards to energy expenditure and appetite regulation, will be examined. HC and IC have identical amino acid composition, but differ in absorption rate, whereas HC and IWP have similar absorption rates, but differ in amino acid composition. We hypothesize that consumption of HC will increase DIT and fat oxidation to a greater extend that IC. Moreover, that HC and IWP will increase satiety shortly after protein consumption, whereas IC will be more satiating after several hours.

The study is a controlled, randomized, 3-arm crossover study. It consists of three visits in a respiratory chamber separated by at least two weeks. 26 healthy, overweight and obese (BMI 27-35 kg/m2) young men will be enrolled and randomized to the order of the three protein supplements (HC, IC or IWP). At each visit protein supplements (containing either HC, IC or IWP) will be served as breakfast, lunch and dinner. Respiratory measures will be obtained over 24 hours and appetite will be assessed by visual analogue scales and appetite regulating hormones. Furthermore, ad libitum energy intake will be assessed.