QUESTION:

Hello, I'm a 5'9" 142 pound female.  Over the last year I have lost 45lbs, and feel great. But now belly is loose and flabby. Is that because skin has been stretched? Have had three kids...will sit ups help, or is it something I have to just live with? Thanks!

ANSWER:

It is more difficult to answer, not knowing your body fat percentage estimate but at your height and weight it sounds like your body fat percentage is pretty low.  There is still a chance that your body fat can be reduced thus shrinking your belly fat stores located beneath your skin.  If this is the case, a full body exercise program and regular cardiovascular exercise is more important for lowering your body fat stores than 'sit-ups.'

As with most women who have multiple pregnancies and gain and lose as much weight as you did, there is also the good chance that you will have loose skin which was stretched beyond its capacity to heal which cannot be improved by anything other than plastic surgery.

There is also a chance your stomach muscles are not as tight and toned (beneath the fat) which is causing your stomach to protrude forward causing your tummy to appear fatter than it is, in this case performing a full repertoire of exercises for the upper/lower abdominals, inner/outer obliques and transverse abdominis (deep core muscles) could tighten your mid section, hense reducing the size of your stomach and making the skin to appear tighter.

You can read more here:

100 Abdominal Exercises