A recent series of studies shows that whey protein taken before a meal decreases overall food consumption during the meal. The most recent study confirms this effect and provides additional insight into how much whey protein is required to elicit this effect.
In the first study, subjects were tested on four separate visits. At each visit, subjects consumed a standardized breakfast. Then at 10:45 a.m., they received a shake containing either a placebo (with zero calories and zero protein) or a shake containing 400 kcal made up of either 13%, 25%, or 50% of whey protein (13g, 25g and 50g of whey protein respectively).
Ninety minutes after ingesting the shake, subjects were provided a pasta-based lunch and asked to eat as much as they wished.
There was a tiered reduction in the number of calories consumed at lunch as the percentage of protein increased in each whey shake.
The effect was stronger in men than women. For example, men who ingested the 50g protein shake ate 450 Calories less during lunch, whereas women who ingested the same shake ate only 200 Calories less.
The reason for the greater effect in men remains unclear, but regardless of gender, both men and women consumed less after drinking a whey protein shake 90 minutes prior to a meal.