There is an article in Psychology Today describing a study where overweight people were put on a calorie restricted diet and randomized to three groups: low calcium supplements (pills), high calcium supplements, and dairy supplements at a level of calcium equal to the high calcium supplement group.

On a calorie restricted diet, the low calcium group lost 6.4% of their body weight. The high calcium group lost 7.7%. But, surprisingly, the dairy group lost 10.9%, and specifically in their abdomen.