> Apparently acetic acid _does_ have calories. Didn't know that.
Calories are measured by burning the substance. While it very precisely determines contained energy in the physics sense, it's a question whether all that energy is used by digestion? Especially if it's something the body treats as a toxin and wants to remove as soon as possible?
A bit pedantic but burning is a chemical reaction, and redox reactions are redox reactions no matter where they're happening.
Also, substances like ethanol and acetic acid are not digested, they pretty much just go straight into the bloodstream. There is a limit on how much e.g. ethanol the liver can process per hour, which does put a cap on how many of ethanol's calories are released as ATP + body heat. Acetic acid is a normal temporary metabolite though and so its consumption is much more complete (it gets used by cells all over).
Calories are measured by burning the substance. While it very precisely determines contained energy in the physics sense, it's a question whether all that energy is used by digestion? Especially if it's something the body treats as a toxin and wants to remove as soon as possible?