A new study shows those over 65 should continue with diet and exercise, dispelling a traditional belief that weight loss can cause the elderly to lose muscle and bone mass.

The researchers, led by geriatrician Dennis T. Villareal, looked at 93 obese patients over the age of 65. Those who were on a restricted-calorie diet and participating in a 90-minute exercise routine three times a week did the best, losing 9% of their weight. That group also retained lean body mass, increased their oxygen consumption and improved their strength and balance. While the diet-only group achieved weight loss, those participants did not have a similar overall improvement in health. Those who were in the control group or only exercising did not show any physical improvements or weight loss. The results are published in the March 31 edition of the New England Journal of Medicine.

It is estimated that at least 20% of the elderly are obese, a number that is expected to grow. In addition to increasing the risk of cardiovascular disease and diabetes, obesity can cause numerous other physical side effects.

“Obesity exacerbates the age-related decline in physical function, which causes frailty, impairs quality of life, and results in increases in nursing home admissions,” researchers noted in the study.