Tone Up and Slim Down With... Heavier Weights?

Conventional workout wisdom will tell you to tone your muscles and slim your waistline, you should use lighter weights and perform more reps.

A New York Times article, however, looking at two studies on female resistance training found that lifting at about 70 to 80 percent of maximum ability burns more energy and promotes greater fat loss. 

Researchers from one of the studies, which followed subjects over six years, concluded resistance training was a viable method for preventing post-menopausal weight gain and changes in body composition.

It seems that lifting heavier weights fewer times resulted in an oxygen demand similar to that created by lifting the smaller weights more times.  And women who lifted as high as 85 percent their maximum ability have been shown to burn twice as many calories in the hours following a workout than when they lifted at a lower weight.