Hi KZALESKI: Good to see you posting on the SP Message Board.
Ask the server to not bring the stuff that is automatically brought as soon as you sit down: bread, chips with salsa, peanuts, or whatever. If you are with people who want to eat that stuff, you are out of luck on this one.
Ask for a to-go container up front and then pack away at least half of what they bring you before you start eating.
Eat some meat or eggs before you go. This will do amazing things to the appetite that otherwise can turn your evening into a pig's dream.
Order only one alcoholic beverage and sip it slowly. Make it last.
Talk a lot to your companions so that your mouth has less time to chew.
If the group orders an appetizer that is really high calorie (like something fried with a high fat sauce for dip), order another appetizer that is less costly to your eating program. If there is no suitable appetizer, order a soup or salad to come when the others get the appetizer. If the salad has some ingredients that don't fit into your plan, ask that those ingredients be left off.