Depression: Abnormal weight loss is a common symptom of depression, which can lead to a decrease in appetite and subsequent weight loss. This diagnosis is likely due to the high prevalence of depression in the general population.

Diabetes Mellitus: Uncontrolled diabetes can lead to weight loss due to the body's inability to properly utilize glucose, resulting in the breakdown of fat for energy.
Hyperthyroidism: An overactive thyroid gland can increase metabolism, leading to weight loss despite increased appetite.
Gastrointestinal Disorders (e.g., celiac disease, Crohn's disease, ulcerative colitis): These conditions can lead to malabsorption of nutrients, resulting in weight loss.
Chronic Infections (e.g., tuberculosis, HIV/AIDS): Chronic infections can cause weight loss due to increased metabolic demands and decreased appetite.

Cancer: Various types of cancer (e.g., pancreatic, lung, stomach) can cause weight loss due to tumor effects, decreased appetite, or metabolic changes. Missing a cancer diagnosis can be fatal.
Neurodegenerative Diseases (e.g., Alzheimer's disease, Parkinson's disease): These conditions can lead to weight loss due to decreased appetite, dysphagia, or other symptoms.
Addison's Disease: This rare endocrine disorder can cause weight loss due to adrenal insufficiency, which can be life-threatening if left untreated.

Pheochromocytoma: A rare tumor of the adrenal gland that can cause weight loss due to increased metabolic rate.
Whipple's Disease: A rare bacterial infection that can cause weight loss due to malabsorption.
Amyotrophic Lateral Sclerosis (ALS): A rare neurodegenerative disease that can cause weight loss due to muscle atrophy and decreased appetite.