By Kim Duke, NETA & AFAA Certified Trainer 

Weight loss boils down to a simple equation: Expend more calories than you take in. With that, eating well and doing cardio is the fast track to success.

But, when it comes to reshaping your body, there’s a totally different way to get results: strength training.

“The number on the scale is where you want it, but maybe your butt is still saggy or your tummy not quite as taut.… Less cardio and more lifting fixes that,” says Holly Perkins, a strength and conditioning specialist and founder of, a resource to inspire women to get in the weight room.

So why do less cardio?  For one, cardio is catabolic; too much of it increases production of the stress hormone cortisol, which, over time, slows down your metabolism and throws off how your body manages carbohydrates by shuttling them to be stored as fat.  Also, cardio doesn’t have the muscle building effects like strength training does.  When you run, you engage your butt and legs, but it’s not enough to break down the tissue prompting the muscle to rebuild stronger and firmer like weighted squats can do.

So how much weight should you be lifting?

For starters, Perkins recommends you lift weights heavy enough so you can do 12 to 15 perfect reps of any move, but no more.

“The weights you’ll be lifting will trigger big muscle growth,” she says, and it will make your metabolism active, which will help you burn more calories.  “This training also causes muscle fibers to swell, so they look toned,” says Perkins.

Dense muscle is tighter than fat, which is why your weight can stay the same even though you may drop a full size.  As little as two sessions a week for ten weeks can reduce overall body fat by about 3 percentage points, even if you don’t cut a single calorie. That translates to as much as three inches total off your waist and hips.

Although cardio burns more calories than strength training during those 30 sweaty minutes, pumping iron slashes more overall.

A study in The Journal of Strength and Conditioning Research found that women who completed an hour-long strength training workout burned an average of 100 more calories in the 24 hours afterward than they did when they hadn’t lifted weights. At three sessions a week, that’s 15,600 calories a year, or about four and a half pounds of fat—without having to move a muscle.

What’s more, increasing that afterburn is as easy as upping the weight on your bar. A study published in Medicine & Science in Sports & Exercise found that women burned nearly twice as many calories in the two hours after their workout when they lifted 85 percent of their max load for eight reps than when they did more reps (15) at a lower weight (45 percent of their max).

For the greatest calorie burn, aim for total-body workouts that target your arms, abs, legs and back, and go for moves that will zap several different muscle groups at a time—for example, do squats, which call on muscles in both the front and back of your legs, as opposed to leg extensions, which isolate the quads.

And remember to fuel your workout properly. Too many dieters make the error of cutting back on crucial muscle-maintaining protein when they want to slash their overall calorie intake. The counterproductive result: They lose muscle along with any fat that might have melted away.

Sports nutritionist Cassandra Forsythe, Ph.D., co-author of The New Rules of Lifting for Women, recommends that you eat one gram of protein for every pound of your body weight that does not come from fat. For instance, a 140-pound woman whose body fat is 25 percent would need 105 grams of high-quality protein. That’s roughly four servings a day; the best sources are chicken or other lean meats, soy products, and eggs.

Ready to turn yourself into a lean, mean, calorie-torching machine? Then go get pumped!