It's not full calories that can be metabolized by the human body, though, that's the point.
I've always had the same question regarding alcohol. Alcohol has a lot of calories, but I've never been able to conclusively figure out whether those calories are actually metabolizable. It seems to me that since alcohol is broken down by the liver, it should be a net drain on calories.
Perfect, if you are powering specific lab engines. Not perfect if you are powering an animal. Can someone explain to me where the confusion is here?
To explain further, since further explanation is obviously needed: There is the physical calorie, which is ONE THING, and then there is the vernacular, "nutritional" calorie", which is something ordinary people deal with day-by-day. They are VERY different, in that kerosene calories and celery calories are handled differently by the human body.
Again, very simple until it comes up against people who don't interact often with reality.
1) There is no confusion -- the physical and nutritional calorie are the same thing (EXCEPT that the nutritional calorie is usually the kilocalorie, or Calorie with a capital c, while the physical calorie is the plain old calorie). You have to remember that the calorie is an abstract unit.
The human body is a gigantic chemical engine, but it operates in a different way from a (jet/propulsive) engine.
It's like the difference between LiOn and NiCad batteries. You measure them both in volts or wattage output or hours, but they operate in fundamentally different ways -- you can't use the same chemical mixtures, even though those mixtures have the same potential energy as measured by some abstract unit.
Err... it is. What's your point? Caloric content is completely unrelated to toxicity, and I don't see any reason why it should be.