Maybe calcium isn’t the key to weight loss after all.

There could be a multitude of factors in dairy products — or just one magical compound — that is responsible.

That is the conclusion from a study published in January in the Nutrition and Metabolism journal. Researchers found that a high-calcium diet containing nonfat dry milk reduced weight gain in obese mice better than high calcium alone. In fact, high calcium by itself didn’t really help, and may have made matters worse.

If calcium isn’t the factor behind weight loss, what is?

Researchers in the mouse study (cited above) say that further investigation is needed.

Greg Miller, president of the Dairy Research Institute and executive vice president of the National Dairy Council, says there are many different factors in dairy products, such as whey protein or branched chain amino acids, which might explain the weight-loss advantages. “Conjugated linoleic acid is another potential bioactive that may have an effect on body fat accumulation,” he says.