You might be confused, the highest value is generally what we call fats. Sugars (aka carbohydrates) have the same calorie density than proteins (broadly speakin

You might be confused, the highest value is generally what we call fats. Sugars (aka carbohydrates) have the same calorie density than proteins (broadly speaking, it seems to heavily depend on the metabolism of each individual, the type of food, etc.) That's why you would rather bring nuts/peanut butter and crisps to a ultralight hike and not a bag of sugar or candies.