[xurukefi]

I would define caloric density as the ratio of calories to weight. Refined sugar has a caloric density of 3.87 (387 kcal per 100gr), which is quite high. Most vegetables and fruits will probably have a caloric density <= 1. But I would also classify something like chicken breast (1.65) or turkey meat (1.89) as "low" in terms of caloric density. But it's not really about setting a threshold. It's more about being aware of how many calories you actually get per gram of food. It can make quite a big difference.