Weights vs. cardio - which works best for burning more fat and calories? Hmm... good question.
I'm exaggerating when I say that nations have gone to war about this issue, but I do it to emphasize its controversy. Let me just start out by saying that they both serve their purpose and have their exclusive benefits.
The real question is, "What are your goals?" Coming to terms with what you're trying to accomplish is really what determines which modality best serves you.
Ideally I would say training with weights and doing cardio is your best bet to achieve overall fitness. They namely target different systems. Cardiovascular exercise strengthens the lungs, vessels and heart, while weight training uses the stamina of cardiovascular exercise to build muscles that support skeleton and organs.
That being said, there are some things you should know.
After the age of 20, our bodies lose 1/3 to 1/2 pound of muscle tissue per year. Of course, this results in strength reduction, as we would expect. The slowing of our metabolic rate translates into weight gain.
So If I had to choose one of the two to counterbalance this effect, it would be strength training. (And I'm not just saying that because I'm a personal trainer!) Strength training is the best and surest way to increase your metabolism, burn fat and sustain long-term weight loss.
Without building muscle you will have a harder time burning body fat. Body fat is "burned" in the muscle. The cardio will burn calories for you directly, more per session than weight lifting because it is continuous work. The weights will cause your muscles to grow which will increase your metabolism - you will burn more calories during the day just to maintain the larger muscles. But weight! I mean wait!
I can see some women turning their nose up at the sound of larger muscles. I can assure you this doesn't mean you'll look like an NFL linebacker. Building muscle is relative to how you're training: higher reps with lighter weights and minimal rest for toning, or lower reps with heavier weights and longer rest for bulking up.
Know this: Each pound of lean body mass, which includes skeletal muscle, burns about 7-15 calories a day at rest. There's a myth out there that says it burns 35-50 calories.
So if you're running like a lab rat to lose weight, you'll get there quicker and more efficiently if you add some strength training exercises. I would say for the average person, strength training 2-3 three times a week and doing cardio 3-5 times a week is ideal. If you're doing them on the same day and session, I would suggest doing the weight training first, being that if you fatigue yourself after cardio, chances are you're not going to push yourself for strength training.
Keep in mind that you can burn as many calories as you like with exercise, but if you eat them back, you won't lose weight.
NOTES: Some exercises are generally for the physically fit and active. If you suffer from joint pain, or have cardiac-related problems, please consult a physician before starting a routine. Otherwise, seek an experienced personal trainer for proper techniques.
For more information, check out www.ammoathletics.com.