LIFTING - Come on then!

Bump.

I would also like to know how 'heavy' heavy is. Specifically what type of lifting for: arms, core and thighs. How many times a week you should be doing, reps etc.

"Heavy" means 80-90% of the maximum you can lift (your one-rep-max, or 1RM). You should be lifting weights so that you fail in the neighborhood of 6-10 reps.

Lifting builds and maintains muscle mass, which is extremely important metabolically. Lifting significantly strengthens bones and prevents osteoperosis. At a given weight, a woman with 18% body fat will look firmer, smaller, and shaplier than a woman with 25% body fat who will look droopy, saggy, and fatty. Lifting strengthens joints and improves posture.

Lifting is extremely important.

As for which lifts, there are a variety of effective training routines out there, but they all incorporate the same 5 fundamental lifts:

The squat
The bench press or pushup
The overhead press or handstand
The deadlift
The row or pullup

You can do each of these exercises once a week and build enormous amounts of muscle everywhere on your body. In all seriousness, I suggest finding a powerlifting gym and picking up a copy of a book like Starting Strength, Convict Conditioning, or Jim Wendler's 5/3/1. These exercises are non-trivial to perform, so you need to know what you're doing. These books will teach you, but it's also best to have people who know how to do them around - and a powerlifting gym is where you find these people. "Trainers" generally have no clue how to do these exercises, because typical gyms simply won't let them. It's much harder to injure yourself on one of those pointless machines typical gyms have, so typical gyms encourage/force people to use the machines. They are pointless - never use them for anything but targeted accessory work.

Of course, most women won't ever do that, which is a shame. But for women who want awesome, shapely thighs and butts along with a flat stomach and shapely arms? The squat, deadlift, bench press, overhead press, and pullup will do unbelievable things to your body.

This is what these 5 exercises, and these 5 alone, can do to your body. This is a real life example:
http://i51.tinypic.com/dc6mfp.jpg

Read this thread:

http://www.myfitnesspal.com/topics/show/896786-general-comment-about-people-who-don-t-lift

The many benefits of lifting are discussed.

I lift.. I started with the machines and moved to free weights..now do a combo of them. I lift as heavy as I can. The dumbells range from 15 to 30lbs depending the move. Machines 30-130lbs depending on the machine.

I don't spend all day at the gym either. I probably avg 30 mins of weights when I go.. 3-4 days a week.

I just started reading "The New Rules of Lifting for Women".... so far so good.

Girls should not be scared of lifting weights. The impact it has on body composition in females is amazing, take a look at some female olympic lifters in the lighter weight classes - not an iota of freakishness about them. My girlfriend used to be a 'cardio bunny' until I got her doing heavy squats and deadlifts and she achieved the toned legs/nice butt she wanted from the start.

Advantages: Increased metabolism, increased strength, 'toned' body, strengthens bones & joints, the list goes on.
Disadvantages: Zero.

I would define heavy training as any weight that causes failure at around the 5-8 rep range. There isnt a specific weight - only what is heavy for your own standard. But this also depends on the exercise - i generally like to stick to very heavy, low reps for movements that recruit the greatest amount of muscles (eg. deadlifts, squats, bench press, row, etc.), and then as less muscles become involved, the reps go up. As jonnythan said, Starting Strength, 5/3/1, 5x5 are all awesome programs and definitely a good starting point - just be sure to invest the time in learning the lifts either by someone you know is experienced with weight training, weightlifting/powerlifting clubs, crossfit gyms or even via youtube videos (be careful though!).

Once you get into lifting and see the true beauty of it, you'll never look back!

Crossfit is an interesting beast, and one you need to be careful about. The philosophy is great and if the place has good instructors/leaders it can be fantastic and fun and non-intimidating. But if they're not that great, the place can devolve into madness where people do crazy stuff in highly non-optimal and dangerous ways.

Of course. Im not a fan of crossfit in general, but I do respect its not threatening environment for girls that just wanna train with weights without being stared at. Always pays to do research on the credibility of any place first.

So advantages and disadvantages of lifting?

I'm not lifting weights yet - I don't have access to any, so I'm starting with body-weight exercises.

However, I want to lift weights and my biggest reason will be to protect my bone-density as I age. A dear friend suffers greatly from osteoporosis, and I don't ever want to be in that position.

Lifting heavy is based on your capabilities. You can start with body weight exercises like push-ups and squats. For me, when I started push-up (as in one not even plural) was hard for me. And once I got to a place where I could actually do a few pushups, I moved on to this:

http://www.nerdfitness.com/blog/2009/12/09/beginner-body-weight-workout-burn-fat-build-muscle/

Now I am starting going to the gym and using actual weights. It is about making it progressively harder, relative to your own abilities.