You can certainly still go out for dinner. It will require some adjustment from you in the sense that it is convenient to order just a starter or a smaller portion. Most restaurants are very willing to see together with you what is feasible to eat for you.
Some tips when you eat out:
- Drink no alcohol
 - Do not eat appetizers
 - Only drink before and after the meal
 - Omit the starter, or take the starter as your main meal, the quantity is ideal.
 
- Ask for the sauces separately
 - Have a coffee instead of dessert