Is it water weight?

So I have been working out since March. I was working out by running , mountain climbing , squats. Etc I would cut down almost anything except chips.. Later I realized that I wasn't losing nothing and I was working out for no reason. Barely 2 weeks ago I was working out again , but this time I was cutting out All the sweets , junk food , fast food etc. I started eating clean. I started noticing that my clothes started fitting a little lose. I weight 144 and now I weight 140 .. I don't know if this is water weight like most people say.
Is it water weight?
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