Hi,
Welcome to Health Care Magic, thank you for posting your query . I understand your concern.
Umbelical
hernia does cause bulging of the abdomen, and the surgery is done with the placing of the mesh . And even after surgery the bulging does not go away completely. So your husband is not fooling you with this.
But you say he weighs 320 pounds which is quite something, and it cannot be due to hernia alone. His over eating habits, non-exercising might be contributing to it too.
Its good to get an abdominal scan done to rule out the excessive bulging of his stomach . This would help us rule out causes other than plain obesity.
Do consider consulting a physician for the same.
Meanwhile ask him to cut down on junk/ oily food/ alcohol/ and bakery products.
A healthy well balanced diet with good regular exercise will help him to lose a couple of pounds.
Consult a dietician to help you choose a suitable menu, and follow it regularly.
Hope this helps and answers your query satisfactorily,
wishing you good health.
do write back to me if you need further assistance.
Take care,
Regards.