|Your account||Today's news index||Weather||Traffic||Movies||Restaurants||Today's events|
Wednesday, August 25, 2004 - Page updated at 12:00 A.M.
Got weight? Get more dairy
By Shari Roan
With recent trends toward low-fat, then low-carb diets, Americans have come to view dairy products as high-fat, calorie-rich foods that have no place in a dieter's kitchen. After all, whole milk, cheese, yogurt and such are naturally packed with fat, and even some nonfat dairy products, like milk, are high in carbohydrates.
It's best to leave such products for children who need calcium to build bones, many believe.
Now a new diet book, a TV ad campaign endorsed by dietitians and a growing body of research suggest the opposite: Calcium products, specifically dairy foods, could help people lose weight.
The claim may not be as far-fetched as it seems: Calcium is critical to cell functions throughout the body. Diets low in the mineral appear to set off a chain reaction that prompts the body to metabolize fat less efficiently.
The sooner the public knows about calcium's effect on weight, the better, says one national expert in calcium metabolism.
Though he acknowledges that the science behind the theory is incomplete, Dr. Robert P. Heaney, a professor of medicine at Creighton University in Omaha, says that if everyone got adequate dietary calcium three to four servings a day while controlling calories, Americans could lose an average of 15 pounds.
At Purdue University, a summer camp is testing whether a calcium-rich diet can help adolescents lose weight. Milk, yogurt and cheese pizza are all on the menu.
The camp began in 1990 to study calcium metabolism in teens, particularly with regard to bone health. But the recent research led Purdue researchers to shift their attention to weight.
Of course, not all nutrition experts are convinced that increasing calcium intake is a panacea for people wanting to shed pounds. More study is needed, they say.
"I'm not totally sold," says Berdine Martin, a nutrition researcher and director of Purdue's Camp Calcium. "But the earlier studies have been convincing enough for us to want to look at it."
Early evidence dismissed
The idea that dietary calcium could trigger weight loss was dismissed when first raised in the early 1990s. Scientists believed adding calcium to the diet could simply help lower blood pressure. Then researchers found that prescribing two cups of low-fat yogurt a day to a small group of hypertensive men led to lower blood pressure and an average weight loss of 11 pounds in one year.
The study author, Michael Zemel now the leading proponent of calcium and weight loss and the author of "The Calcium Key" couldn't explain the result and didn't publish his findings.
Still, he believed he was onto something, and the University of Tennessee researcher eventually found a plausible explanation:
With a calcium-poor diet, the body makes more of a hormone called calcitriol, Zemel suggests. Calcitriol causes the body to hoard calcium by sending more calcium into fat cells, which signals them to store more fat. The calcium tells the fat cells to be more efficient possibly an evolutionary trait to protect the primitive human body.
With a calcium-rich diet, Zemel says, calcitriol production decreases and less calcium is shuttled to fat cells. Less fat is stored.
In Zemel's most recent study, published in the April issue of Obesity Research, 32 overweight adults were put on modest, calorie-restricted diets that included varying amounts of dietary calcium. The high-dairy patients lost the most weight, an average of 24 pounds after 24 weeks, compared with those who cut calories but consumed few or no dairy products. The study was funded by the National Dairy Council.
Though some experts think calcium could play a role in weight loss, they aren't all sold on Zemel's explanation. Others suggest calcium somehow binds with fat in the body to inhibit absorption. Still others say adding daily dairy to one's diet could make people feel full, so they eat less.
Other studies, in groups as varied as teenage girls, post-menopausal women and middle-age men, support the connection. In a study presented at an American Heart Association meeting in March, Boston University researchers found that children with the lowest intakes of dairy products gained much more body fat over an eight-year period.
"The evidence gets progressively stronger," says Heaney, whose analysis of nine studies by various researchers found a connection between higher calcium intakes and lower body fat or body weight in children and adults. "It's a consistent finding. Every time somebody looks for it, they see it. But it's a small effect, so if you didn't look for it specifically, you might not notice it."
The 24/24 meal plan
The theory may be the subject of scientific interest because it's so attractive, some experts suggest.
Adding low-fat milk, yogurt and cheese to the diet while cutting calories slightly is a safe way to lose weight that, unlike fad diets, can be maintained for long periods, they say. Moreover, there's widespread agreement that Americans get too little calcium to foster good bone health.
"So many Americans don't really get enough calcium in their diets. We felt this would be a good opportunity," Susan Laramee, president of the American Dietetic Association, says of her group's endorsement of a dairy diet.
The ADA, the nation's largest organization of food and nutrition professionals, began promoting a dairy-based diet called the 24/24 meal plan this year in conjunction with Milk Processor Education Program, an industry group funded by milk processors. The 24/24 meal plan consists of 24 ounces of dairy products, such as three glasses of milk, consumed in 24 hours as part of a 1,600-calories-per-day diet.
"It's a well-balanced diet that provides a relatively moderate amount of calories. For most people, it's enough to lose weight," Laramee says. But she acknowledges that the calcium weight-loss theory is unproven and that more studies free of dairy-industry support should be done.
Although much of Zemel's work has been funded by the dairy industry, most researchers say the science is solid. And several other studies, some of which found a link between weight loss and calcium and others that didn't, have been done free of industry support.
Calories still important
Dairy products may play a role in weight loss, but cutting calories is essential, Zemel says.
"We still have to worry about calories," he says. ... We're not dealing with a magic bullet."
The diet won't help overweight people lose weight if they are already getting adequate dietary calcium. Among those not restricting calories, the diet may stabilize weight, he says. And too much dairy, like too much of most anything, will increase calories to the point of weight gain.
Critics of Zemel's approach and the 24/24 plan suggest cutting calories alone can cause a slow, steady weight loss and that calcium may have nothing to do with it. "You would expect a person, on average, to lose about a pound a week on a calorie-restricted diet," says Dr. Amy Joy Lanou, nutrition director of the Physicians Committee for Responsible Medicine.
Will supplements work?
Another major question surrounding the diet is whether calcium supplements work as well as dairy products. So far, the answer appears to be no, Zemel says.
Some scientists have proposed that certain amino acids in dairy products help preserve muscle mass, thus contributing to the body's fat-burning process, Heaney says. And some Atkins diet proponents suggest that certain dairy products, such as cheese, trigger weight loss because they are high in protein and low in carbohydrates.
In a study published in February in the Journal of Clinical Endocrinology and Metabolism, calcium supplements were found to be useless for weight loss and fat metabolism in adult women. But lead author Sue Shapses believes a dairy-based diet could work.
"I wouldn't dismiss this entirely," says Shapses, an associate professor of nutrition at Rutgers University in New Jersey.
"The bottom line for me is that this diet is not going to do anything bad to people. This diet is at least safe."
Copyright © 2004 The Seattle Times Company
Home delivery | Contact us | Search archive | Site map | Low-graphic
NWclassifieds | NWsource | Advertising info | The Seattle Times Company
Back to top