One meal a week isn't going to derail what you do the rest of the week. What you do for the other 20 meals and 14 snacks is going to make a much bigger difference!
When eating out, you can check the nutritional information for many restaurants online before you even get to the location. If it's a local place, pick a national chain that is similar, and use that information.
When eating at someone's house, make sure you have a good snack before you go (high protein and fiber, like 2 sticks of string cheese and an apple), and plan the rest of your meals that day knowing you'll be eating at that person's house. So if it's your health-conscious in-law doing the cooking, eat what you normally do. If it's a family member who loves to serve deep fried chicken, butter-topped mashed potatoes, and nary a green in sight, load up on veggies and lean proteins the rest of the day and plan to eat a reasonable serving size.
Don't worry so much about tracking for just one meal per week. I let myself have "no-track" days when I know it's going to be difficult because of where I'm eating or my schedule. The important thing is to remain consistent during your other meals and days of the week.
Simple things you can also do include sticking to water to drink, and filling your plate of the available vegetables and fresh fruits.
Take life one day at a time - enjoy today before you worry about tomorrow.
| current weight: 222.0