In the year 2016, more than 340 million children and adolescents aged between 5 and 19 were overweight or obese, says WHO. Obesity is defined as excessive fat accumulation in the body that can lead to serious health hazards. Your weight is characterized by your Body Mass Index (BMI). A person is called overweight if he has BMI greater than or equal to 25. However, he will be called obese if his BMI is greater than or equal to 30. Obesity has become one of the greatest causes of concern these days. And, that is why people all around the world are obsessed with exercises and fitness diets to lose weight. Weight loss can be achieved by reducing total body mass. It has various physical and psychological health benefits. However, if you are experiencing sudden unexplained weight loss, it can be a cause of concern too. If you are not exercising or dieting and still loosing body mass, there is something wrong with your body and its metabolism. There are several factors or conditions that lead to this problem. Read on to know about them.