He said that working out cardio at you target heart rate for x amount of time jumpkicks your metabolism into working for a few hours after. Then he said, if you do cardio for less time and then add weight training/lifting the metabolism stays with you for much longer.
Combining cardio with weights and combining steady state (ss-cardio) with high intensity interval training (HIIT-cardio) is far more efficient.
Lifting weights will help you build muscle (and no, you won't bulk up - women don't have the testosterone in their bodies that allows them to bulk like men. women who bulk have to WORK at it really hard with weights and diet). Muscle is metabolically active - so that means that the more muscle you build, the more calories you burn, even at rest.
HIIT cardio also creates an "afterburn" effect, where you continue to burn extra calories for several hours after your workout, whereas ss-cardio doesn't raise your metabolism in that way.
When I added weights and HIIT to my exercising it's like my weight loss took off again. Also my entire body shape changed. I said this in another thread just this morning ... I look better now at 160 and lifting weights than I ever did at a skinny and out of shape 120.
Also, I do believe you can start out with HIIT.
Does that mean you can do 6 cycles of it for 20 or 30 mins. Nope. Sometimes *I* can barely do 30 mins of it.
But even one or two cycles of HIIT is beneficial and before you know it you'll be doing more and more and more. Don't ever say "you can't" ... because if you say it, that's the way it'll be. Start slow and build up and you can do almost anything!