Some evidence suggests that high calcium consumption in the form of dairy foods can promote weight loss, but that doesn't mean that all you have to do is drink lots of milk. Here's the story:
Researchers at the University of Tennessee found that calcium stored in the fat cells of mice can help determine their metabolism. In one study, the researchers fed obese mice a high-fat, high-sugar diet for six weeks. The animals' body fat increased by 27 percent. Then the researchers put the mice on different low-calorie diets. They also gave one group calcium supplements, another group dairy foods, and the third group just the low-calorie diet. The mice in the third group lost only 8 percent of their new body fat; the mice that received calcium supplements lost 42 percent, and the mice that got dairy products lost 69 percent of the fat they had put on.
When the same researchers tried similar tactics on obese people, the ones who lost the most weight were the ones whose diets included dairy products. This study was sponsored by the National Dairy Council and published in the April 2004 issue of Obesity Research.
Meanwhile, a study at Creighton University in Nebraska showed that over a 20- year period, women whose intake of dairy foods was highest had an average weight gain of zero while those whose dairy intake was lowest gained a pound per year.
The latest word on this subject comes from Purdue University where a recent study showed that calcium intake in the form of dairy foods didn't make a difference to weight one way or the other. Researchers followed 155 women between the ages of 18 and 30 for one year, tracking their calcium intake and weight. They found that none of the women gained or lost weight, no matter how much calcium (in the form of dairy products) they consumed. The study was published in the April 2005 issue of the American Journal of Clinical Nutrition.
I think the jury is still out on this one. But I can tell you that you won't lose weight by adding yogurt or some other type of dairy product to what you're eating now. However, if you replace some of the calories in your diet with yogurt or other types of dairy products, over time you may see a difference.
Andrew Weil, M.D.