If you have unintentionally lost more than 5% of your normal body weight, or more than 10 lbs (4.5 kg) in 6 – 12 months or less, you should consult your doctor. In people with diabetes, insufficient insulin prevents the body from getting glucose from the blood into the body’s cells to use as energy. Unintentional or unexplained weight loss can be caused by a number of things, including depression, certain medication and diabetes.