Ever since Dr. Atkins introduced the concept of the low-carb, high-protein diet in the 1960s, Americans have been obsessed with finding the perfect protein. For many, that meant lean choices such as chicken or fish.
Then came the 1990s and the “milk mustache” campaign, which proclaimed milk a great source of calcium as well as protein. People quickly jumped on the dairy bandwagon, touting the benefits of low-fat cheese, yogurt, and just plain, ole milk.
Next came the minute dairy discussion: casein versus whey protein. Casein is the primary protein found in milk. In fact, it makes up about 80 percent of milk’s total protein and is described as a “slow” protein, as it takes your body a bit longer to digest and absorb casein.
Whey is also a milk protein, though not as abundant as casein. It is best known as a by-product of cheese making and a “fast” protein, meaning it is quickly digested.
Dairy By Any Other Name…
Many studies have examined the effects of casein or whey on weight-related biomarkers. For example, some research shows casein to be better at providing a feeling of fullness, while other researchers found that whey was more satiating than casein. Still others found that milk itself stimulates the production of biomarkers that indicate satiety better than whey alone.
Given this, Danish researchers set out to compare the effects of milk, whey and casein on satiety, as well as diet-induced thermogenesis (metabolism) and oxidation. 
Researchers studied 17 moderately overweight but healthy men between the ages of 18 and 50. All subjects received three different meals on three different days, with at least one week’s time between test days.
All participants ate normally on non-test days. They were asked to avoid alcohol or hard physical activities 48 hours before each test day. The night before each test day, the men ate a standard meal that consisted of spaghetti Bolognese, orange juice and crackers. They were not allowed to eat or drink anything other than 17 ounces of water after the meal.
On the morning of the test day, all participants were weighed and their appetite was assessed. They were then asked to eat a test meal, which consisted of bread, butter, jam and the chosen test drink (either whey, casein or milk). They were then asked about the palatability of the meal and appetite. And they were tested for energy expenditure and appetite every 30 minutes for four hours.
After four hours, participants were given a pizza lunch and told they could consume as much as they wanted. Researchers noted how much was eaten, the number of calories consumed, and the palatability and appetite sensation after lunch.
Milk Does a Body Good
When all test meals were completed after about a month’s time, researchers found no significant difference in palatability of each test meal, satiety, appetite sensation, fullness or hunger between the milk, casein and whey. Similarly, there was also no difference in terms of energy expenditure, oxidation or diet-induced thermogenesis.
However, there was one significant difference: The amount of calories consumed after the milk-based meal was lower than those eaten after both casein and whey meals. This means that while participants stated that they felt equally satisfied after all three meals, in reality they ate less after the milk meal than the other two meals.
Researchers hypothesized that this may be due to the “unique combination of the ‘fast’ whey and the ‘slow’ casein in milk proteins.” They also went on to suggest that milk likely contains other currently unknown bioactive components that affect appetite sensation.
Regardless of the reason, they concluded, “Milk is more satiating than whey or casein alone.”
Got Milk for Weight Loss?
Based on these findings, it appears that milk does, in fact, help you control your weight and can be included as part of a healthy diet. Aim for four 8-ounces glasses per day (just shy of the 1,000 grams used in the study). Look for options that contain at least 7 grams of protein and up to 13 grams of fat.
 Acheson KJ et al. Protein choices targeting thermogenesis and metabolism. Am J Clin Nutr. 2011;93:525-34.
 Hall WL et al. Casein and whey exert different effects on plasma amino acid profiles, gastrointestinal hormone secretion and appetite. Br J Nutr. 2003;89:239-48.
 Diepvens K et al. Different proteins and biopeptides differently affect satiety and anorexigenic/orexigenic hormones in healthy humans. Int J Obes (Lond). 2008;32:510-18.
 Lorenzen J et al. The effect of milk proteins on appetite regulation and diet-induced thermogenesis. Eur J Clin Nutr. 2012;66:622-7.