I was on a 900 calorie per day diet about 22years ago (when i was 21) ... i went from 66 to 50kilo's in 7weeks (lost 16kilo's)... just ridiculous & to think that was through the help of a weight lose centre that had just started up it's business ...

It got to the point that i felt i wasn't eating hardly anything and strangely enough i lost my appetite for food and began even eating less to the point i was losing 3kilo's per week in the last fortnight on the program ... just insane ... luckily one of the consultants picked up on this

Anyway, the outcome was i put ALL the weight back on in about 2mths plus more

I never went down that road again ... as i could see i was getting use to not really eating ... very dangerous ... So, I say 500calories NO WAY !!!