I'd start a class with a check of what folks had for lunch or breakfast as kind of a funny ice-breaker but also clue as to how that person might fair 3hrs down the line. I was blown away once by a very skinny mom and teen'age son that thought nothing about starting a 2:00 class with nothing but snickers bar for him and 1/2bagel for her at breakfast. The both were chilled to the bone after being in 75degree water and 80degree air after a few rescues. Some of my best classes came from getting in the water next to a person having a dificult time re-entering and finding out where they can get a purchase and kick to get back in whether weight,age,strength,or fear was the issue. Now Weight-Watchers might have been a good thing for me a few years ago trying to paddle with beer,coffee, peanut butter, V-8 juice,kippers, beer and power bars in my gut. Doing yoga inversions with ones belly to look at is a conversation in itself, where'd that come from? do I know you?.
Paddle to eat, eat to paddle. whatever floats your boat.