One study, done by David Ludwig, of Boston's Children Hospital, and Dr. Walter Willett, of the Harvard School of Public Health, says that people who drink low calorie beverages are likely to eat more because the lower calorie drinks are less filling.
Another article in Time magazine reports that "a study published in the Archives of Disease in Childhood in March, scientists found that kids who drank lower-fat milks were actually more likely to be overweight later on. The article goes on to say:
"Our original hypothesis was that children who drank high-fat milk, either whole milk or 2% would be heavier because they were consuming more saturated-fat calories. We were really surprised when we looked at the data and it was very clear that within every ethnicity and every socioeconomic strata, that it was actually the opposite, that children who drank skim milk and 1% were heavier than those who drank 2% and whole," study author Dr. Mark Daniel DeBoer, an associate professor of pediatric endocrinology at the University of Virginia School of Medicine and the chair-elect for the AAP Committee on Nutrition, told TIME in March.
The Daily Mail story also points out that full fat milk only has 3-4% fat, which isn't really very much.
And so, if you're looking to maintain a healthy diet, perhaps the best thing would be to eat things in their natural state rather than reduced fat versions, and just to eat less of the other crap that's the real problem.