Albert Buitenhuis, who weighs 286 pounds, was told that it may place demands on the New Zealand health services.
He and wife Marthie are now facing deportation from their Christchurch home and are living with his sister in Auckland as they fight the decision.
New Zealand is the third most obese nation in the developed world, coming behind the US and Mexico.
Albert is five feet ten inches tall and has a body mass index of 40, making him clinically obese.