Dissolved sugar is probably invisible or close. Can you see a difference between a glass of Coke and a glass of Diet Coke? One has 140 calories and the other ha

Dissolved sugar is probably invisible or close. Can you see a difference between a glass of Coke and a glass of Diet Coke? One has 140 calories and the other has nominally zero. That's not to say you couldn't approximate it and tell someone they ate a Twinkie today which is more fattening than the steamed broccoli they had yesterday. And you could probably help people manage their diet better with an app that could do that. But it's always going to be an approximation with a potential for large error in certain cases.