Dutch researchers examined the effects of whey protein consumed at breakfast on subsequent diet-induced energy expenditure and satiety. Men and women consumed three breakfasts in random order that contained on average a little over 400 calories.
The control breakfast was whole milk yogurt consisting of 15%, 47% and 38% energy from protein (16g), carbs and fat. The second breakfast was an equal calorie but higher-protein meal including whey protein, which consisted of 41%, 47% and 12% energy from protein (42g), carbs and fat. The third breakfast was the same as the second except it included whey protein enriched with added alpha-lactalbumin beyond the naturally occurring levels found in whey.
Compared to the control breakfast, the two high protein breakfasts with whey and whey rich in alpha-lactalbumin resulted in increased thermogenesis (21% and 30% respectively) during the four hour period after the meal. In addition, hunger and desire to eat were suppressed to a greater degree after the meal containing whey alpha-lactalbumin.
These findings provide evidence that a breakfast with whey protein promotes increased energy expenditure compared to a lower protein breakfast. The fast rise in leucine levels found in whey may be the key to increasing thermogenesis and decreasing hunger.