I think it has to do with two elements.
1) Your current level of activity. How much or little actual exercise do you get? For how long? How intense is the exercise?
2) Your current way of eating. I'm not talking about a diet, because diets are temporary. I'm talking about the way you eat every day! What do your meals revolve around? How often do you eat? How much?
These two things help determine the answer to your question.