Lost 20 pounds in a week?

💓 • Momma w a 13 month old 💙

I posted this on another group but got no answers, I just started working out and eating healthy maybe a week and a half ago, I started as 179 and I just weighed myself now I'm 158. Would most of that weight just be water weight since I lost it so fast? I can't notice a difference just by looking at me, I think I look the same as I did when I weighed 179