Unintentional weight loss may indicate an overactive thyroid and type 1 diabetes, UK endocrinologists Kristien Boelaert and David Cavan have told The Daily Mail, the latter reports.

Dr. David Cavan, a consultant endocrinologist at University Hospitals Dorset, noted that diabetes is often associated with obesity and overweight. However, these pathologies are not directly related. Moreover, weight loss is a common phenomenon in type 1 diabetes.

According to the physician, changes in body weight are associated with impaired insulin function. Insulin is a hormone that transports glucose from food into cells, where it is stored as a source of energy. In type 1 diabetes, the pancreas produces insufficient insulin—or none at all, and this depletes fat stores and muscle tissue.

In addition, in this disease, the body tries to eliminate excess glucose by producing more urine. Fluid loss can lead to dehydration, which can lead to weight loss.

Unexpected weight loss can also indicate problems with the thyroid gland. Kristien Boelaert, a professor of endocrinology at the University of Birmingham, noted that this small organ produces iodine-containing hormones (iodothyronines), such as tetraiodothyronine and triiodothyronine. An excess of some of them can lead to accelerated metabolism and weight loss—despite an increase in appetite.

The physician added that other signs of thyroid dysfunction include a faster—sometimes irregular—heart rate, shaking of the hands, tiredness, and diarrhea.