Obesity is a serious problem, especially in America. Not only are there countless health risks, but thousands of people also die each year due to obesity. However, thousands of people die from car accidents and shootings. Just because something has an effect on human bodies, doesn't make it a disease.
For example, food poisoning has numerous symptoms such as stomach pain, diarrhoea, and vomiting. It can even lead to death in some cases. Food poisoning is due to ingesting spoiled food or drink, so that means it is caused by the human's actions. Obesity has numerous symptoms, can end in death, and is caused by a person's actions. Neither are a disease.