Yes it is more complicated. Here's two reasons. Glucose only gets converted to fat and harmful proteins at about 1:4 rate, whereas ethanol, fructose, and sucrose get converted to fat and harmful proteins at double or more that rate. So mere "counting calories" is meaningless.

Secondly, and this is the one that people find weird, once you've weighed X pounds, and lost some significant mass, you must eat less calories than simple "calories in is calories out" would suggest, because our physiology reacts as if food is scarce, and will store fat to the detriment of all other functions.