There are several definitions for the term "flab," but most agree that it is soft, fatty, hanging tissue on various parts of the body, particularly noticeable in the mid-body and on the arms. Possibly the main difference between fat and flab is that flab is the visible result of fat. On the other hand, some people view flab as the soft hanging skin that may result after people have lost significant weight. Loose skin is a problem for many people who lose a lot of weight, and there are disagreements on how best to correct this issue.

For the most part, loose, flabby skin contains fat, making it looser and more noticeable. Flab is also possibly an expression of poor muscle tone. When people do not have enough muscle mass, the surrounding tissue may look loose and untoned. Flabbiness can be a combination of the two, where extra body fat combined with poor muscle tone creates a saggy, and in many people’s estimation, unflattering appearance.

When diet experts or fitness gurus discuss fat and flab, they typically state that people are less flabby when they have smaller underlying fat cells. In order to get rid of flab, the thing to do is reduce fat levels in the body and increase muscle tissue simultaneously. This strategy may work well, especially if people have only carried weight for a short time, such as during a pregnancy, and particularly when people are under 30.

If flab is due to skin that has been stretched out, particularly for long periods time, the medical community often suggests that even large and healthy amounts of fat loss will still leave residual flab or hanging skin. Some fitness experts believe that even in people with reduced collagen and elastin, this hanging skin can be reduced with additional fat loss and building of lean muscle mass. According to some, fat and flab can still be lost simultaneously.

There is disagreement as to whether such methods may work, and many people opt for surgical removal of flabby areas, especially after pronounced weight loss. Many people opt for this remedy because the flab may remain despite the patient's best efforts, and may be unsightly and uncomfortable. Presently, there are few studies that account for how much of “flab” or loose skin removed contains actual fat, and if this type of fat reduction improves appearance. Generally, the medical community suggests exercise and diet for people with a small amount of fat and flab, but might recommend surgical measures for removal of a lot of skin after large amounts of weight loss.