Losing weight without trying might sound like a dream come true, but in reality it can signal a health problem. If you're not obese and you've lost more than 10 percent of your body weight during the past six months — for instance, 15 pounds (7 kilograms) if you weigh 150 pounds (68 kilograms) — consult your doctor. An unexplained drop in weight could be caused by various conditions — including overactive thyroid (hyperthyroidism), diabetes, depression, liver disease, cancer or disorders that interfere with how your body absorbs nutrients (malabsorption disorders)...Consult nearest physician they will do the needful.