People looking to lose those extra pounds have been told for decades that dieting together with exercise will bring about the best results. Not so, according to new research published in the Journal of Clinical Endocrinology & Metabolism, which reveals that dieting alone is as effective as dieting plus exercise. The key is in the calories, and the study shows that calories can be lost effectively by either dietary restrictions or exercise.
"For weight loss to occur, an individual needs to maintain a difference between the number of calories consumed everyday and the number of calories burned through metabolism and physical activity," says Leanne Redman, PhD, first author of the study and clinical research fellow at the Pennington Biomedical Research Center in Baton Rouge, La. "What we found was that it did not matter whether a reduction in calories was achieved through diet or burned everyday through exercise."
The researchers conducted a randomized, controlled trial to examine the effects of diet alone or diet plus exercise in overweight but otherwise healthy study participants. The participants were divided into three groups. One group only reduced caloric intake. A second group reduced caloric intake by a smaller amount, but included exercise as part of their program, and a third set of participants served as a control group. They were all followed for a six-month period.
At the end of the study, the reduced-caloric-intake group and the group that combined a smaller amount of reduced calories with exercise had similar results. Members of both groups lost roughly 10 percent of their body weight, 24 percent of their fat mass, and 27 percent of their abdominal visceral fat, which is fat buried deep in the abdomen and linked to heart disease risk.
The shape of a person's body, as well as his or her body weight can be indicators of the risk for cardiovascular disease. Some studies have shown that people with "apple-shaped" bodies, or more fat distributed at the waistline, may have a higher risk of heart disease than people with "pear-shaped" bodies, or more fat at the thigh or hips.
"Researchers are working to understand how abdominal fat and subcutaneous fat, which is fat located closer to the surface just beneath the skin, differ in response to the body's need to use fat for energy," says Sherry Marts, PhD, vice president of scientific affairs for the Society for Women's Health Research in Washington, D.C. "It is known that, on the whole, premenopausal women who gain fat add it to the subcutaneous fat, mostly on the hips and thighs. Men and women after menopause tend to add fat to the deeper reserves in the abdominal area."
Increased levels of fat in the abdomen are linked to a higher risk of cardiovascular disease, but the precise influence of this visceral fat is not yet understood.
Despite the fact that weight loss can be achieved equally through diet or fitness, according to the study, both are important for a person's overall health. Weight loss isn't the only reason to diet and exercise. Regular exercise has been shown to lower your risk for many diseases including: heart disease, type 2 diabetes, and certain types of cancer. In addition, many experts recommend that permanent weight loss should be achieved with consistent dietary restrictions, low-caloric and low-fat foods, and regular exercise.
But if you're looking to tone certain areas of your body with exercise, think again! The researchers also discovered that fat distribution was not affected by either approach. The exercise group was not able to eliminate fat in certain parts of the body. So much for sit-ups!
"We found that fat is reduced consistently across the whole body and not more in any one part," says Redman. "We found some evidence in other studies that suggested the way in which we store fat is linked to our genetics, and our study then would indicate that weight loss cannot override the way in which any individual stores fat. Perhaps an apple will always be an apple, and a pear, a pear!"
Researchers are now trying to determine how sex hormones and being a man or a woman affect fat distribution.
"The roles of hormones," Dr. Marts said, "such as estrogen, progesterone, and testosterone in fat deposition and loss are not yet understood, but research in this field is advancing rapidly."
The answers to those questions may hold the keys to a healthier life for everyone.
Redman L, Ravussin E. Effect of calorie restriction with or without exercise on body composition and fat distribution. Journal of Clinical Endocrinology & Metabolism, doi:10.1210/jc.2006-2184.