Can Calcium Help Me Lose Weight?
Denis M. Medeiros, Ph.D., R.D.
Professor and Head
Department of Human Nutrition
Kansas State University
For quite some time, researchers have known that calcium is important for bone development and protecting against the bone disease osteoporosis. There has been a lot of research that shows that calcium-rich diets can lower blood pressure among hypertensive subjects (people whose blood pressure is too high).
Recently there has been more interest in the role that calcium may play in obesity. In one study, obese African Americans were followed over a one-year period to determine whether their blood pressure could be reduced. One group was given yogurt every day, which raised their calcium consumption from 400 mg per day to 1000 mg per day. This resulted in an average weight loss of almost 11 pounds over the course of the year. Survey studies have also suggested that people who weigh more and are more obese also have the lowest calcium intakes. African Americans (in survey data) have the lowest levels of calcium intake and have the greatest incidence of obesity.
Animal and human studies lend support to the idea that a diet high in calcium may reduce weight. Research has demonstrated that dairy products tend to be more effective than calcium supplements at achieving this benefit. Researchers have been trying to determine why calcium may have this anti-obesity impact. The general idea is related to how much calcium is inside the cells of our bodies. And here's where we come up against a real problem in logic.
More calcium inside a cell means more fat "synthesis" occurs, which actually results in greater body fat, or obesity. But wait a minute....Haven't we been saying that calcium might help reduce body fat and obesity? What's going on here? It appears that the key is to include plenty of calcium in your diet, but keep it out of your cells. Which isn't as hard as you might think!
Let’s back up a bit and look at some more research about calcium. In a study of 32 obese people, a University of Tennessee group studied the effects of both calcium supplements and extra calcium from dairy products. The subjects were divided into three groups for a 24-week trial.
- The control group took 400 to 500 mg of calcium per day through their diet, along with a fake calcium supplement (placebo).
- The calcium-supplemented group took 800 mg per day in a calcium carbonate pill along with a diet that added some calcium for a total of 1200 to 1300 mg of calcium per day.
- The high dairy group ate three servings of dairy products per day and took a placebo supplement (no extra calcium).
The subjects on all three diets lost weight. The control group lost about 6.4% of their initial weight. Those in the second group (who took a calcium supplement and also ate some calcium in their diet) lost 8.1% of their initial weight. The third group, which took in calcium from only dietary sources (mostly dairy foods), lost 10.9% of their initial body weight, the biggest drop of all.
So why does extra calcium in our diet make us lose weight if extra calcium in our cells makes us gain weight? And how does that extra calcium get into our cells in the first place? Researchers believe that the culprit in this equation is vitamin D. Vitamin D is a nutrient we all need in our diets. However, when calcium levels are high in our diet, we do not make as much vitamin D. When calcium is low in our diet, we make more vitamin D. And one of the roles of vitamin D is to increase calcium levels in the cell—which we've already noted above will cause the cells to make more fat. So eating a diet higher in calcium actually reduces calcium in your cells and can help reduce your weight. It's a complicated domino effect...but true!
I hope the message you take away from all this is that the evidence is rather strong to support the fat-lowering effects of dietary calcium, particularly from dairy products. Like Mom said, drink your milk.
References
- Zemel MB. J. Am Coll Nutr 21: 146S-151S (2002)
- McCarron DA, Morris CD, Henry HJ, Stanton JL. Science 224: 1392-1398 (1984)
- Fleming KH, Heinbach JT. J. Nutr. 124: 1426S-1430S (1994)
- Zemel MB, Thompson W, Milstead A, Morris K, Campbell B. Obesity Res, 12: 582-590 (2004)