Generalizations... just that. When people say exercise just makes them more hungry etc., I believe it. But it's just one of those things that can happen, and we don't know that it will happen to everybody. Damage the hypothalamus one, way, you might get a lethargic animal, normal appetite, another way, increased appetite same activity levels, another way... not that we're all explained by damaged hypothalamuses, the point is just that regulation of body mass isn't a simple linear system, where decreased food intake inevitably leads to decreased activity levels (though it seems to work that way for me personally, but eating more ketogenically even within low carb weakens the effect) or increased activity inevitably drives food intake up--again, it may be a common enough occurence, but it's not a simple system, it's just one possible outcome to that input.