A June 8, 2005 release from "HealthDay News" reported on a study of 104 men and women that participated in six months of aerobic exercise using a bicycle, treadmill or stepper, combined with weightlifting. The results of this study were better overall fitness and fat loss without significant change in bone mineral density. In fact the researchers found that participants who exercised the hardest and had the greatest increases in aerobic fitness, muscle strength and muscle tissue showed bone mass increases of 1 percent to 2 percent.
Co-author and endocrinologist Dr. Suzanne Jan de Beur, an assistant professor at Johns Hopkins University, said in a statement, "Fat loss with exercise did not result in a loss of bone mass, a problem commonly seen when patients lose weight with diet alone."
Lead investigator Kerry Stewart, professor of medicine and director of clinical exercise physiology and heart health programs at Johns Hopkins University School of Medicine and its Heart Institute, explained, "Older people are very concerned about how best to reduce their body fat as a means of preventing other health problems, such as heart disease and diabetes. However, excess fat does have the benefit of maintaining bone mass." She added, "But fat loss through diet alone can lead to loss of bone, worsening the body's natural bone loss due to aging, a major risk factor for bone fractures."
Dr. de Beur recommended that older people should either exercise at a higher level of intensity or for longer than six months in order to achieve a substantial increase in bone density. She stated, "Our results show that moderate-intensity exercise can increase fitness and reduce body fat, which are important for overall health, but gains in bone density were found only among those who achieved the greatest gains in fitness in six months."