Technically, it’s defined as loss of body mass due to loss of fluids, adipose tissues or lean mass like bone deposits or muscles. A sudden weight loss is cause for concern unless you are on a conscious weight loss program. Unexplained weight loss could mean that there is something wrong with your body. In such cases it is always better to go in for a medical check-up. Or at least consult your doctor. Conscious weight loss programs generally relate to getting rid of excess fat in your body. This is done by controlling your diet as well as doing regular exercises. But even this should be done under the supervision of trained professionals because losing too much of weight suddenly can raise health alarms.