I think you're okay Jenn... go to the FAQ section of South Beach and review the Emergency Handbook for Phase 1... In general part skim and LF cheese is okay -- look for cheeses that are less than 6% fat ... (just check to see that when lighten stuff up it is not replaced with sugars) Here's an extract from the food list in that Emergency Handbook
CHEESE (FAT-FREE OR LOW-FAT)
Look for varieties that have 6 grams of fat or less/ounce
American
Cheddar
Cottage cheese, 1-2% or fat-free
Cream cheese substitute, dairy-free
Feta
Mozzarella
Parmesan
Part-skim Ricotta
Part-skim String
Provolone