your daily goal...??how do they work it out?

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So when entering what food you're eating etc... there at the bottom states your daily goal..i understand the rest but that one.. in the sense that, where /how do they figure out what your daily goal is?

i see the word GOAL as something to reach... im not eating enough to reach that goal...because i get heaps more with my exersize that im doing.. so if i reach that goal, like use up all my points (for lack of better word) and not go over, does that mean ill still lose weight?..or if you use them all up, is that saying.. youve just reached equilibrium with ur daily exersize so u wont lose or gain? am i making sense?lol