Jerry: Maybe your yogurt isn't so non-fat.
Kramer: Oh, guess again, Tubby!
Elaine: Jerry, there's got to be a way to find that out.
Jerry: There must be some kind of lab that would do that kind of thing.
All it would take is for some enterprising news crew to go over to said restaurant, purchases said meal, and take it to an independent lab for a full calorie analysis.