[eru]

One trivial stabilizing mechanism is that more bodymass needs more power even at rest. So if you were perfectly balanced now with your current diet and current weight, and added the same snack every day, the only change would be a slight one time gain in weight.

Different foods make you eat more or less, by eg filling you up faster or keeper you satiated (and satisfied) for shorter or longer. So if you want to test your hypothesis, you'd have to carefully control for these effects, in order to rule out that caloric input is king. (I.e. my null hypothesis here is that caloric input is what counts in the end, but different foods have an influence on how many calories you actually consume.)

Anyway, the caloric surplus was just a simple example. Perhaps a clearer example would have been `trying to gain weight through fasting'.