Is a glue stick technically food?
I don’t know the amount of calories in a glue stick, but technically the correct way to find out would be to burn a gluestick in a calorimeter. As Oxydude said, just because something has calories doesn’t mean that the body can use the energy contained in the substance as food.
The problem with defining food as Wikipedia does is that some things that are distinctly NOT food CAN be consumed for pleasure and even have (some) nutritional value. I don’t know how many calories a gluestick has (so perhaps this will get deleted) but you and your friend might want to look into a disorder called pica which occasionally affects, among others, pregnant women. (Wiki defines it as “an appetite for largely non-nutritive substances (e.g., coal, soil, feces, chalk, paper, etc.) or an abnormal appetite for some things that may be considered foods, such as food ingredients (e.g., flour, raw potato, starch)”.) A friend of mine had it and found herself in her garage eating dry wall when she suddenly realized that perhaps something was amiss.
The Elmer’s FAQ links to MSDS sheets for their products, and the glue stick appears to be made out of a mixture of “synthetic polymers.” Other parts of the FAQ suggest that these polymers are probably derived from fossil fuels, although the exact ingredients are “proprietary.” So, it appears that there are probably no human-digestible calories in a glue stick. I would assume, for the purposes of your argument, non-human-digestible calories presumably don’t qualify as “nutritional content.
A problem with categories in natural language is that they are typically vague, to the point where they do not actually have necessary and sufficient conditions. This is why many psychologists have turned to things like prototype theory (and its descendents) to account for the way humans classify things. These theories are “graded” in the sense that categories are not exactly discrete. We can talk about things being “good examplars” of food, and there will be things that are very clearly food, but the borderline cases will be difficult to determine. Most traditional definitions in e.g. dictionaries try to impose necessary and sufficient conditions, just as the wikipedia definition dmd posted does. For a category like “food”, it will be extremely hard, if not impossible, to find such conditions that a gro
The glue stick might make you sick to your stomach, rendering the caloric content moot. Traditional paper glues are made from flour (library paste) or casein-based (milk protein), but commercial makers add preservatives to make sure that bacteria and fungi won’t use the glues as food. The same goes for trendy fruit-based and milk- or nut-based shampoo and bath products, which contain preservatives and detergents. Soak and eat your leather shoes and belts first, if you are stranded on a desert island, before eating your glues and your shampoos. This also reminds me of Primo Levi’s account of, when he was an enslaved chemist in Auschwitz, trying to synthesize something edible from the laboratory’s supplies.
