USAWMom - I hate to ask what age and weight your child is that you would allow him to lose 5 lbs. Hopefully he is older and had it to lose.
Not only as a mother, but as a healthcare professional, I would never allow his wrestling to interfere with his overall well-being. We are a wrestling family and have made a lifestyle change to support his decision to lose the weight and keep it off. It is not a diet or a quick fix, but a lifestyle change for the entire family.
He discussed it with his coach and together they chose for him to drop two weight classes (5lbs) over the course of a month. My son will never sleep/run in garbage bags or be deprived of a meal. We understand that sometimes sacrifices must be made, but not at the expense of my son's health.