I need some advice on weight loss/5:2 diet

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So ive posted a few times about this 5:2 diet (which was recommended by my GP), and some people think its a waste of time. I did manage to lose over a stone last year and lose a few inces but finding it hard to get back into it after xmas.

Last year i tried eating 1200 a day and lost nothing - not even an inch. I tried for two months. Someone said 5:2 was pointless just add up the calories you have been eating, so normal day i eat 1600 and 5:2 day id eat 500 - roughly 1200 a day. This is the same as what i was eating before i started 5:2 but someone how my body liked it ??

What im asking here is... do people think I should continue with 5:2 and eat 1600 on a normal day and 500 on a 5:2 day or.... eat 1200-1300 a day in calories each day and two days a week eat little to no carbs on those day ... that is the only thing i can think of that my body must have liked potentially ?

Id really like some input from people who have an insight to weight loss :)

Cheers in advance !!!