Weird Loss

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So I got weighed a week and a half ago at the hospital and I was 75.4 Kilos.
Gave me the shock i needed (Gained 10 kilos in 6 months) I needed to get back to gym, give up my nightly binge drinking and fast food hangover meals.
I've been feeling excellent, lots of energy, generally happy :)
However I got weighed again yesterday on the same scales and was 71 kilos.
Is this just water weight? Or am I not as bloated without the 5000+ Calories a week in Alcohol ?