You have not given a lot of information, such as if your cat goes outside, his vaccine status, or if you have taken your cat to a vet recently. Answers to these questions and others would help us to help you and your cat.
There are many reasons for a cat to lose fur and weight. Common causes include fleas and flea allergy dermatitis, which can cause excessive hair loss, but you would be aware of scratching or chewing at the fur and skin. Fleas also carry tape worm which could cause your cat to lose weight. Other causes are food intolerance/allergy, which cause skin issues and gastro-intestinal symptoms. Endocrine disorders and auto-immune diseases and infectious diseases (skin fungal or bacterial infections) and other skin or gastro-intestinal parasites can also cause the symptoms you describe, amongst many other causes. Therefore you really must take your cat to the veterinarian for an exam and diagnostic procedures.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.