In one of the first studies to examine the role of dairy and soda consumption on weight in adolescent girls, researchers from the University of Hawaii report that girls who consumed more dairy products weighed less than their peers who ate the same number of calories. Drinking soft drinks was also associated with increased body fat.
"The simple message from this study would be that teens need to exchange milk for soda if they are concerned about weight," lead researcher Rachel Novotny, PhD, tells WebMD. "The girls who consumed more soda were heavier, even though they ate the same total number of calories."
According to government health figures, 15% of the teens in the U.S. were overweight in 2000, compared with 10% just a decade earlier. Between 1965 and 1996, milk consumption among teenagers declined by 36% while the consumption of soft drinks almost doubled.
The newly reported study included 323 white and Asian girls between the ages of 9 and 14. The girls were asked to record everything they ate for three days, and physical activity history was also recorded along with weight. The researchers also measured skinfold thickness to determine body fat.
Girls who consumed more dairy products were found to have slimmer middles than girls of the same age and ethnicity who ate the same number of calories and got the same amount of exercise. Girls who drank more soda, but also ate the same total calories, tended to be heavier. The findings are published in the September issue of the Journal of Nutrition.
"We know that where fat is distributed on the body is important to future health," Novotny says. "People who tend to put fat in the middle -- the apple shape -- have greater health risks. This research suggests that eating dairy is associated with a healthier fat distribution."
The findings add to growing evidence suggesting that dairy foods like milk, fat, and cheese are important players in regulating body fat. University of Tennessee nutrition professor Michael Zemel, PhD, was one of the first to report on the association. His latest research suggests that dieters who eat dairy-rich foods lose almost twice as much fat as those who eat the same number of calories but consume little or no dairy.
Zemel tells WebMD that while calcium appears to be an important component in the storing of body fat, eating three to four servings of dairy a day is a better way to maintain a normal weight and get calcium's benefits than taking calcium supplements. An 8-ounce glass of milk is generally considered a serving, as is a cup of yogurt and 1.5 ounces of hard cheese.
The researcher says several mechanisms appear to play a role in dairy's ability to influence body fat. A hormone known as calcitriol, which helps the body regulate calcium levels in the blood, also appears to stimulate human fat cells.
The more calcium there is in a fat cell, the more fat the cell will burn -- and the greater the weight loss.
"When we don't have enough calcium in the diet, that sends two messages to fat cells," he says. "One is to make more fat and the other is to slow down the process of fat burning."
Both researchers emphasized that calorie restriction is still important for weight loss.
"Calories definitely count," Zemel says. "You can't just add dairy foods if you are already eating too much. You have to replace other foods and eat the appropriate number of calories."