Drinking skim or low-fat (1 percent) instead of whole milk seems to promote obesity in children, according to a meta-analysis in the American Journal of Clinical NutritionAs summarized by Nicholas Bakalar in the Times: 

“Canadian researchers analyzed 14 prospective studies including 20,897 children up to 18 years old. The studies compared children who drank whole milk (3.25 percent fat) with those given milk containing less than 2 percent fat.

“Combining the data from these studies, the scientists calculated that compared with children who drank low-fat milk or skim milk, those who drank whole milk were at a 39 percent reduced risk for overweight or obesity, and the risk for obesity declined steadily as whole milk consumption increased.

“The authors speculate… It may be that children who drink whole milk consume fewer calories from other food. Some studies suggest that milk fat has properties that make people feel full. Reverse causality could also be at play: It’s possible that skinny children have parents who offer them whole milk to fatten them up.

Our vote is for explanation B, milk fat has properties that make people feel full, i.e., satisfied.