Can anxiety cause 30 pounds of unintentional weight loss in 4 months and loss of appetite?

Weight loss: Yes , anxiety can cause your weight loss. However, you should have a complete examination to rule out other problems like hyperthyroidism, or tumor

Possibly but ..: Severe untreated anxiety or mood disorders can cause significant weight loss but it's quite uncommon, especially when you are taking about 30lbs in 4 months. You need to see your doctor urgently to better evaluate you for other organic causes of which are many. I wouldn't delay this as you even if you don't have a more concerning organic cause of your symptoms then you need to addres your anxiety!