April 17, 2000 -- Got milk? New research suggests you should if you want to lose weight. The study shows that calcium -- three or four daily servings of low-fat dairy products -- can help adjust your body's fat-burning machinery.
The key is low-fat dairy sources, says lead author Hang Shi, a postdoctoral student in the Nutrition Institute at the University of Tennessee at Knoxville. "High-fat dietary calcium can establish obesity, but it's surprising that low-fat calcium may help reduce body fat," Shi tells WebMD. "The effect is very significant, much more than we imagined it would be."
His paper on the effects of a high-calcium diet in increasing body fat loss was presented at the Experimental Biology 2000 meeting in San Diego.
"The magnitude of the findings was shocking," says Michael Zemel, PhD, director of the Nutrition Institute, who is Shi's co-author and doctoral supervisor.
In their past studies, Zemel and colleagues have shown that calcium stored in fat cells plays a crucial role in regulating how fat is stored and broken down by the body. It's thought that the more calcium there is in a fat cell, the more fat it will burn.
The researchers used mice bred to be obese in their current study. The mice were fed a special high-fat, high-sugar diet for six weeks. All had a 27% increase in body fat.
Some were then switched to a calorie-restricted diet. Of those, one group was given calcium supplements (calcium carbonate similar to Tums) and others were fed "medium" and "high" amounts of low-fat dry milk.
Body fat storage was markedly reduced by all three high-calcium diets, say the authors.
Those given calcium supplements had good results, when combined with the restricted-calorie diet. Mice getting their calcium via supplements had a 42% decrease in body fat, whereas mice eating without supplements had an 8% body fat loss.
However, calcium from dairy products produced the best results. Mice on the "medium-dairy" diet had a 60% decrease in body fat, while those on the "high-dairy" diet lost 69% body fat. Researchers also found very small increases in thermogenesis -- the body's core temperature -- which then enhances the effects of calcium gained through diet rather than calcium in supplement form, says Zemel.
"Calcium is no magic bullet. What the study says is that ... higher-calcium diets favor burning rather than storing fat. Calcium changes the efficiency of weight loss," Zemel tells WebMD.
The human body's metabolism makes weight loss difficult, he explains. "Many people who stick to a calorie-reduced diet don't lose weight as fast as they think they should. That's because they activate metabolic protection ... Their bodies sense starvation and hang on to energy -- fat -- more voraciously."
Too many dieters tend to immediately "jettison dairy foods from their diet, because they're just sure they're going to make them fat. In fact, they're shooting themselves in the foot, because they subject themselves to more empty-calorie sources. They would be better off if they would substitute high-fat dairy products with low-fat dairy," says Zemel.
Keeping in mind that the mouse study is preliminary, it is very well done and shows promise, Pamela Meyers, PhD, a clinical nutritionist and assistant professor at Kennesaw State University near Atlanta, tells WebMD. "But the calcium amounts the study suggests are effectively equal to what the USDA already recommends as a minimum for adults," she adds.
While nonfat dry milk was used in this study, few people buy that product, says Meyers. "Also, there are people who are lactose intolerant who can't consume dairy products. That's why we need to look at other food sources of calcium, [such as] ... dark leafy vegetables, salmon, mackerel, almonds, and oats. ... They also are very high in fiber, which helps in terms of weight management."
This study was supported in part by the National Dairy Council.
- According to a recent study in mice, a diet that includes low-fat dairy products can aid weight loss.
- Researchers say this is because calcium stored in fat cells plays an important role in fat storage and breakdown.
- Current recommendations encourage men to consume 1,000 mg to 1,200 mg of calcium per day and women to consume 1,000 mg to 1,300 mg daily.