Dear [Aunt's Name],
Thank you for your message and for expressing your concern about Tony. I appreciate your care for him, but I would like to kindly ask that we don't jump to conclusions about his situation. His weight loss is something we're aware of, and it's being addressed appropriately.
I hope you can understand that Tony's health and life situation are personal matters, and I would prefer to keep them private. Your support means a lot to us, and I appreciate your understanding.
Best regards,
[Your Name]