Research presented today at the Experimental Biology conference reveals that yogurt may help turn up the body's fat-burning ability - making it easier to lose fat while maintaining lean muscle.
The new study - presented by Michael Zemel, Ph.D., professor of nutrition at the University of Tennessee - found that individuals who included Yoplait Light as part of their weight loss plan lost significantly more weight compared to others who simply reduced calories. The yogurt eaters lost 22 percent more weight, 61 percent more body fat and 81 percent more trunkal (stomach) fat during the 12-week study.
Zemel and colleagues at the University of Tennessee studied the impact of adding yogurt to a reduced-calorie diet on 34 healthy obese adults who were randomly assigned to one of two diet groups. The Yoplait Light group consumed about 1,100 milligrams of calcium each day, which included three servings of Yoplait Light yogurt. The other low-calcium control group consumed only about 500 milligrams of calcium - or the amount that's typical of the American diet, which is chronically low in calcium.
All subjects received an individualized diet plan that provided 500 fewer calories than their usual intake. Body weight and blood pressure were recorded weekly, and total body composition was assessed before and after the 12-week intervention by dual-energy X-ray absorptiometry (DEXA).
"Not only did yogurt help the study participants lose more weight--the average weight loss was 13 pounds--they were about twice as effective at maintaining lean muscle mass," Zemel said. "This is a critical issue when dieting -- you want to lose fat, not muscle. Muscle helps burn calories, but it is often compromised during weight loss."
Losing Where it Counts
The participants who included Yoplait Light in their diets also lost 81 percent more fat in the stomach area, which is the most dangerous type of fat. "Apple-shaped" obese individuals who carry extra fat around their middle section are at an increased risk of heart disease, diabetes, stroke and some types of cancer. The calcium-rich diet helped the participants lose more than an inch around their waist compared to those on the low-calcium diet. This represented about a six-fold greater decrease in waist circumference.
Evidence is Mounting
Zemel has been a pioneer in this emerging area of research examining the relationship between calcium and weight management. He was the first to discover that small changes in the calcium levels of fat cells alter signals within the cell that control the production and breakdown of fat. Getting enough calcium in your diet seems to trigger the body to burn more fat and reduces the amount of new fat the body makes.
His previous studies have found that in a reduced-calorie diet, as calcium intake goes up, weight and body fat go down. A diet low in calcium appears to stimulate the production of fat-producing enzymes and decreases the activity of enzymes that break down fat, Zemel said. The result is bigger, fatter fat cells.
"The moral of the calcium story is to not dump dairy when you're dieting," Zemel said. "Not only is it critical to keep your calcium levels high so you won't lose bone density, it will also help you maintain your muscle mass and increase your fat loss. A diet rich in lowfat dairy foods, like yogurt, can help make your weight loss efforts easier."
Zemel recommends three servings of dairy foods a day, particularly fat free and lowfat choices. Yoplait Light is a fat-free yogurt that is an excellent source of calcium and contains only 100 calories per 6-ounce serving.
Zemel, M.B. et al. Dairy (yogurt) augments fat loss and reduces central adiposity during energy restriction in obese subjects. FASEB 2003; 17, 5: A1088.