Trying to stay trim as you age? Surprisingly, if you’re cutting calories to lose weight, adding weights to your weight loss regimen may be more effective than beginning a walking program, according to a new study that adds to growing evidence that weight training is important for vigorous aging.

Successful weight loss is never easy, as most of us know from experience, and becomes more difficult with age. Instead of losing or maintaining weight as we grow older, most of us gain a pound or two each year during middle age.

At the same time, we also often begin naturally to lose some of our muscle mass, so that our bodies wind up increasingly composed of fat.

This change in body composition matters, because fat tissue is less metabolically active than muscle. As the percentage of our body composed of fat tissue rises, our metabolic rates fall and we burn fewer calories throughout the day, predisposing us to continued weight gain.