I looked at this field a while back and I'd caution that estimates are dramatically off because high and low calorie foods are often identical visually. Think

I looked at this field a while back and I'd caution that estimates are dramatically off because high and low calorie foods are often identical visually. Think of a diet soda vs a sugared one - it can be 10 vs 1000 calories easily. Almost all diet options are designed to look like the non-diet options.