General Workout to Lose Fat, Firm Up and "Tone"
How often to workout?
Take one to two days off between working out a specific muscle group - so this normally means a total of 3 workouts a week (or 4 times, if you do a routine where you split the workout into upper/lower body routines)
How is Weightlifting different from Aerobic activities?
Think of it like a spectrum. At one end is aerobics, the other, weights, and they overlap in the middle. Aerobics is designed to primarily work the heart and lungs, and the muscles secondarily. Weightlifting is the reverse. Each pound of muscle uses, by itself, about 50 calories per day - even when you are not exercising (See Duke University's research for evidence of this). Since 1 pound of fat is equal to about 3,500 calories, if you gain about 5 pounds of muscles (which is more dense, small than 5 pounds of fat), that means you'll lose a pound of fat ever 2 weeks in ADDITION to those your burn off WHILE exercising! This is why weightlifting brings about changes in appearance, muscle tone and strength faster and to a greater degree than aerobics. Aerobics (James Fixx, a USAF doctor is generally credited with the term) also called "cardio workouts" is designed to work the heart and lungs primarily, not the muscles.
"If you are only doing aerobics, you are missing the boat," says Wayne Westcott, co-author of Specialized Strength Training. "You will lose muscle mass and your metabolism will slow down as you age if you don't strength train." See the full USA Today article