Really??? My assumption was the exact opposite, that stamp glue (some of which will enter your digestive track) has a small amount of caloric content.

Hmm - based on this website, a 200 lb person walking for 3 miles at 3MPH = 300 calories burned. Assuming a step of 2.5 feet, this means that 2 steps burns 0.09 (or ~ 0.1) calorie. I would think wagging your tongue is less exertive than taking two walking steps.

Assuming the stamp glue is carbohydrate/protein, then 0.1 calorie = 25 mg of stamp glue. That seems possible -- 25 mg is a pretty small quantity