Earlier quoted context omitted.
One gram of carbs is 4 calories., so more like 400 calories per hour. It was confusing when the running industry switched from calories to grams of carbs, but that's all anyone talks about now.
It’s also confusing that most nutritional labels say “calories” (Cal) when they really mean kilocalories (kcal). And those are different from regular (‘small’) calories (a measure of energy needed to heat 1g water 1c). 1 food calorie as listed on a food label is enough to heat 1kg of water by 1c
https://www.futilitycloset.com/2008/11/16/the-mensa-diet/
(If the nutritional calories in the drink had been only the same number of thermodynamic calories, the drink would have been energetically negative for the body because of its low temperature.)