In a diet study, 322 overweight men and women, aged 40 to 65, ate a low-fat, low-carb or Mediterranean-style diet. After two years, regardless of which diet, those who consumed 580 mg or more of calcium per day from dairy products had lost about 12 pounds compared to seven pounds for those who got 150 mg or less of calcium per day. Measuring vitamin D, researchers knew from prior studies that overweight people have lower blood levels of vitamin D and, in this study, were able to confirm for the first time that those who lost more weight had higher blood levels of vitamin D.
In another study, 870 overweight, post-menopausal women, average age 66, took calcium with or without vitamin D, or a placebo. The doses were 1,400 mg of calcium and 1,100 IU of vitamin D per day. After four years, the placebo group had gained 5.4 percent trunk fat compared to 2.4 percent for the calcium-only group and 1.4 percent for calcium plus vitamin D. This study shows that to minimize the normal fat gain around the waist that occurs with aging, consume higher levels of calcium and vitamin D.