> I've seen hundreds of grown adults completely jaw-dropping shocked that an massive bowl of salad has the same amount of energy (points in WW speak) as a small piece of chocolate cake.

I think this is the most important part. I'm an adult, I have a PhD in Computer Science (not boasting, just saying I felt like I should be on the more educated side of things), and I still massively underestimated the tomato to chocolate cake calorie ratio when challenged to do so.