I personally don't eat it before lunch (my mum drilled that into me for years) as a general rule.
I don't judge people who do (except my boss, who buys a multipack of chocolate on the way to school - the ones with 3 or 4 bars, has scroffed the lot by the end of period 2 and I have to spend all of break listen to her pondering over why she is the size of a house!)