I'm adding a 2nd bathroom with it's own dedicated 20 amp circuit, 120 volt. There will be one receptical, 2-seperate light fixtures, and one 70 cfm exhaust fan. Can I also add a 1000 watt heater to same circuit?

I definitely would not, but it would be within code.

Thank you for a quick response. If adding a 1000 watt 120 volt heater to a 20 amp circuit is code approved, why would you definitely not? Appreciate opinion.

Because someone can plug a curling iron and hair dryer in and your breaker will trip.

Also, you will have no light in the room if the breaker is tripped for that or any other reason.